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MANUAL 



GENERAL, DESCRIPTIVE, AND PATHOLOGICAL 

ANATOMY, 

BY 

J. F. MECKEL, 

Professor of Anatomy at Halle, &c. &c. &c. 

TRANSLATED FROM THE GERMAN INTO FRENCH, 

WITH ADDITIONS AND NOTES, 

BY 

A. J. L. JOURDAN, 

Member of the Royal Academy of Medicine at Paris, &e. &.c. &.c. 



G. BRESCHET, 

Adjunct Professor of Anatomy at the School of Medicine, &c. &c. &c. 
TRANSLATED FROM THE FRENCH, 

WITH NOTES. 



BY A. SIDNEY DOANE, A.M., 



IN THREE VOLUMES. 
VOLUME III. 




PHILADELPHIA 

CAREY & LEA.— CHESTNUT STREET. 

1832. 



3$ 

v. B 



" Entered, according to act of Congress, in the year 1832, by Henry C. Sleight, in the 
office of the Clerk of the District Court of the Southern District of Now York" 



SLEIGHT AND ROBINSON, PRINTERS, 
No. Ill Nassau St., New- York. 






MANUAL 

OF 

GENERAL, DESCRIPTIVE, AND PATHOLOGICAL 

ANATOMY. 



DESCRIPTIVE ANATOMY. 



SECTION II. 



OF THE PERIPHERY OP THE NERVOUS SYSTEM. 

§ 1809. The periphery of the nervous system, comprehending the 
nerves properly so called, is divided into three sections : the nerves of 
the spinal marrow or the spinal nerves, the nerves of the brain or the en- 
cephalic nerves, and the ganglionnary or great sympathetic nerve. The 
number of these nerves, including the last, is forty-three pairs. But 
anatomists do not divide them in the same manner, for several cerebral 
nerves have been blended which are now considered as distinct pairs ; 
and farther, some consider as cerebral nerves those which others refer 
to the spinal pairs. 

We shall point out the differences arising from the first of these 
sources in our general remarks on the cerebral nerves. Those which 
arise from the second depend principally upon the division of the 
central mass of the nervous system. If the medulla oblongata be 
considered as the summit of the spinal marrow, we must naturally 
arrange the nerves arising from it among the spinal pairs ; hence their 
number is increased, while that of the cerebral pairs is diminished. 

Vol. III. 2 



DESCRIPTIVE ANATOMY. 



Thus Gordon admits only eight pairs of cerebral nerves and thirty- 
four pairs of spinal nerves. Bichat makes three classes, the first com- 
prising two nerves of the cerebrum, the second six of the mesoce- 
phalon, and the third thirty-four spinal nerves. Others with Portal, 
tacitly admit another intermediate class m which the accessory nerve 
is placed, which in the geneial method belongs to that of the cerebral 
nerves. Others as Sabatier, Bichat, and Cloquet, following "Willis, 
exclude the fust nerves of the spinal marrow from the number of spinal 
pairs, and consider them as the most inferior cerebral nerves. 

This last method is the least natural of all, for although the upper 
pair of the spinal nerves is often between the cerebral and spinal nerves 
in character, as may be seen from the description, still it is more like 
the latter than the former. The want of exactness in considering the 
last four cerebral nerves as the first spinal pairs, is also proved by the con- 
tradiction between the general characters of these four nerves and those 
of the spinal marrow, and it then becomes impossible to generalize 
about these last. This classification is farther very inconvenient, since 
a slight examination demonstrates that certain nerves (for instance, the 
auditory and external motor nerves) arise from the same region of the 
central part of the nervous system ; and with a little care and patience 
this may be proved of most of the others. The same reasons which im- 
pelled us to separate the medulla oblongata from the spinal marrow and 
to consider it as a portion of the encephalon, have obliged us to place 
the nerves derived from it among the cerebral. The characters of these 
nerves, which resemble those of the cerebral rather than those of the 
spinal nerves, demonstrate also the superiority of our method. 

We shall first examine the spinal nerves, not only because we have 
already treated of the spinal marrow when describing the cervical part 
of the nervous system, but because from the cerebral nerves, which 
will be mentioned last, we shall naturally pass to the organs of sense, 
and from them to the more complex organs, with which we shall close 
the treatise. 



CHAPTER I. 

NERVES OF THE SPINAL MARROW. 

§ 1810 We have already mentioned the general characters of the 
nerves of the spinal marroio :(1) they are divided into as many sec 
tronsas there are regions in the vertebral column, consequently into 
cervical, thoracic, lumbar, and sacral nerves. 

We shall first describe the thoracic nerves, except the first nno 
because they are more simple and arise the first ; next the nervesnf 
the limbs, those of the inferior extremities arising from most of the 

(1) J. J. Huber, De medulla spinall, speciatim de nervis ab ca n™^ • , ., 
Gottingen, 1741.-G. Frotscher, Dc medulla spinali cjusque nervis, Ed^gTn nee** 



OF THE NERVOUS SYSTEM. 7 

sacral and lumbar nerves, those of the superior from the first dorsal 
and the last four cervical ; finally, the four superior cervical nerves, 
which lead by a remarkable transition to the cerebral nerves. 

Before, describing minutely the nerves of these different regions, we 
ought to make known the following characters which belong to them 
in common, and which are important in regard to their topography. 

1st. There is no constant difference between the nerves of the right 
and those of the left sides. 

2d. The nerves are not perfectly symmetrical ; one is often situated 
higher than another, and the number of cords is frequently greater by 
two or three on one side than on the other. But this difference is 
almost always coiupensatcd for, because then the adjacent pairs vary 
in the opposite manner. 

3d. The upper and lower pairs are much nearer each other than the 
central. The latter also after the last dorsal nerve, are so near each 
other that they do not seem like separate nerves. They are also much 
nearer in the early periods of existence, and even during the first years 
of life, than at subsequent periods. This propinquity in the superior 
and inferior regions, is owing to the disproportion between the size of 
the nerves and the shortness of that part of the spinal marrow from 
whence they arise. Hence why the smaller thoracic nerves, which 
arise not much above the place from whence they leave the spinal 
marrow, are farther from each other, and the reason of the greater 
distance between the spinal nerves in animals whose necks are longer, 
and in whom too the spinal marrow descends lower than in man. 

4th. The ganglions formed by the posterior roots are situated in the 
intervertebral foramina, except those of the sacral nerves which are 
found in the cavity of the sacrum. 

These ganglions are not all of the same size in all regions, and their 
development is not in a direct, ratio with that of the nerves. In fact, a 
ganglion which is usually large, is not unfrequently replaced by another 
very small, and vice versa. The ganglions of the dorsal nerves are 
generally the largest, and those of the sacral nerves, especially the 
last, the smallest. 

5th. All the spinal nerves divide soon after coming from the verte- 
bral column into two branches, an anterior and a posterior, the first of 
which is often larger than the other, excepting always those of the 
second cervical nerve, which presents a contrary arrangement. The 
anterior branches turn first outward, then' forward and inward, and 
terminate near or upon the anterior median line. The posterior go 
directly backward, and are distributed to the muscles which fill the 
groove between the spinous and transverse processes of the vertebras, 
or in those which correspond to them in the cranium and the skin of 
this region. The first are distributed to the anterior muscles, which 
represent these dorsal muscles on the sides and anteriorly, and in those 
of the extremities. 



$ DESCRIPTIVE ANATOMY. 

6th. All the spinal nerves communicate together very constantly by 
one or several larger or smaller branches which they give off soon 
after leaving the vertebral canal, and which anastomose with those 
analogous. 

The anastomosing branches usually arise from the anterior part of 
the nerves, or belong only to their anterior branches, and go before the 
transverse processes on the sides of the bodies of the vertebrae. The 
brachial, lumbar, and sacral plexuses, are formed entirely in this man- 
ner ; their arrangement, however, differs from that usually seen, being 
more complex, since the anastomosing branches produce others which 
anastomose several times with those near. Nerves composed of fila- 
ments from several trunks uf different origins, tuise hum these points of 
union whether single or multiple. 

One or more anastomosing branches communicate at the same time 
with the branches of the ganglionnary system in the limiting gan- 
glions. 

Besides these anterior anastomosing branches which form along the 
vertebral column, a series of plexuses, corresponding in number to that 
of the vertebras, the posterior branches also anastomose in an analogous 
manner, especially at the upper region of the neck, although this ar- 
rangement is less general posteriorly than anteriorly. 



ARTICLE FIRST. 

DORSAL NERVES. 

§ 1811. The dorsal, thoracic, costal, or intercostal nerves (JV. iho- 
racici, s. dorsales, s. costales, s. intercostales) are like the dorsal ver- 
tebras, twelve in number. Some anatomists, however, as Haller,(l) 
count only eleven, and annex to the lumbar nerves that usually re- 
garded as the twelfth. We shall examine only the eleven inferior 
nerves, as it is more convenient to describe the first with the four 
inferior cervical nerves. 

The general characters of these nerves are as follow : 

1st. They make part of the smaller nerves of the spinal marrow, 
and are particularly smaller than the inferior cervical, the lumbar and 
the superior sacral nerves. 

2d Most of them, especially the inferior, are those spinal nerves 
which arise farthest from each other. Still the superior are nearer 
to each other than the superior cervical nerves are 

3d. Most of them communicate only by intermediate filaments in 
the vertebral canal. Still we have often found between the first and 
second pairs, as between the second and third, a filament, proceeding 
obliquely from above downward, and from within outward, from the su- 

(1) El. phys., lib. x. not. 38. 



OP THE NERVOUS SYSTEM. 9 

perior edge of the inferior nerve to the inferior edge of the nerve situated 
immediately above. They have always seemed smaller between the 
second and third pair than between the first and second. 

4th. Their trunk furnishes on emerging, and immediately after, some 
thin short branches which go forward and enter either into the nearest 
limiting ganglion of the ganglionnary nerve, or more rarely into the fila- 
ment of communication between two of these adjacent ganglions. It 
then divides soon after emerging into two branches, one anterior, inter- 
costal, or subcostal (R. intercostalis, s. subcostalis), the other posterior 
or dorsal (R. dorsalis). 

The anterior branch proceeds under the rib, below which the trunk 
comes from the vertebral canal, between the external and internal 
intercostales muscles, and advances as far as these last extend. It 
accompanies the intercostal vessels lodged more or less immediately 
in the groove of the rib. In its course it gradually leaves the superior 
rib, so that its anterior part is nearer the rib below than that above. It 
then perforates the intercostales muscles near the sternum, and be- 
comes external. Proceeding, it gives branches to these muscles, the 
upper part of the abdominal muscles, and to the skin which covers the 
intercostales muscles. These last filaments called the external thoracic 
nerves (R. pectorales extemi), successively perforate the intercostales 
muscles from behind forward, but all arise very far from the place 
where they emerge. 

Each anterior branch near its origin, sends off posteriorly several 
branches, of which the internal are usually numerous, and go, inde- 
pendently of those corning from the trunk, to the limiting ganglions of 
the ganglionnary nerve and their filaments of union, and anastomose 
in this place with the analogous branches of the adjacent dorsal nerves, 
while the external which are simple, pass on the internal face of the 
ribs, and communicate with those of the two adjacent dorsal nerves 
which go to meet them. These last are sometimes deficient in the 
middle pairs : but their absence is not always observed, as they not 
unfrequently occur there, although they are more developed in the 
upper and lower pairs. 

The posterior branch proceeds backward between the transverse 
processes of the vertebrae, between which it arises under the multifidus 
spinae muscle, and there usually divides into external and internal 
branches, the latter of which are. smaller and are deficient when the 
division does not take place. 

The internal branches are distributed to the multifidus spinas, the 
semispinalis, the spinalis, the internal belly of the sacro-lumbalis, the 
digastricus nuchae, the complexi, the transversalis, the inferior portion 
■of the splenius, the rhomboidei, the trapezius, and the latissimus 
dorsi muscles. 

The external branches proceed outwardly, emerge between the 
scalenus muscle and the internal belly of the sacro-spinalis, and in this 
place penetrate between the two bellies of the latter muscle, to which 
they are distributed and also to the superficial muscles of the back. 



10 DESCRIPTIVE ANATOMY. 

Besides, these two branches usually, but not always, extend to the 
skin. 

All the dorsal nerves are not of the same size. Except the first, 
which is the largest, they go on increasing in size much from the 
second to the last. However, they do not enlarge uniformly ; Haller(l) 
and Scemmening have observed, and the results of our numerous dis- 
sections also coincide with their opinion, that the the fourth, sixth, and 
eighth, are smaller than the fifth, seventh, and ninth. 

§ 1812. The differences in the distribution of the thoracic nerves, 
depend principally on their anterior or intercostal branches. 

The first is remarkably distinguished from the others. It soon goes 
upward and outward above the first rib, toward the brachial plexus, 
and opposite to this rib divides into two branches. One which is pro- 
portionally very small, goes forward and proceeds below the first rib 
like the anterior branches of the other thoracic nerves. The second 
is much larger, and ascends and corresponds to the small anastomosing 
branches of the other thoracic nerves ; it immediately unites with the 
brachial plexus, with which we shall describe its farther progress. 

The anterior branches of the second and third thoracic nerve, to- 
gether furnish to the skin of the arm an inferior branch, wdiich may 
be called the brachial nerve. Both then send some filaments to the 
intercostales muscles, penetrate the external, then descend to the in- 
teguments at the axilla and unite, but not always uniformly, with 
the internal cutaneous nerve of the arm, and expand in the superior 
and internal part of the integuments of the arm, so that their filaments, 
especially those of the second pair, descend to the elbow. 

Anteriorly, the anterior branches of these two nerves terminate in the 
anterior part of the pectoralis major and the triangularis sterni muscle. 
In their passage they furnish no constant branches to the abdominal 
muscles. 

The anterior extremities of the anterior branches, and of the 
second, third, fourth, fifth, sixth, and seventh thoracic nerves, are 
distributed also in these two muscles, the skin of this region, and 
the thymus gland. The external pectoral twigs of these branches 
penetrate into the upper part of the obliquus externus and rectus ab- 
dominis muscles, also in the skin which covers them. 

_ The anterior extremities of the anterior branches of the eighth, 
ninth, tenth, and eleventh thoracic pairs, pass above the costal digi- 
tations of the diaphragm, glide between the obliquus interims and 
transversalis abdominis muscles, distribute filaments to these muscles, 
and then go to the posterior face of the rectus muscle and to the skin 
which covers it. 

The external pectoral twigs of these branches are distributed in 
the upper part of the obliquus abdominis internus muscle and the skin 
near it. 



(1) Depart, corf, hum., vol. viii. p. 399. 



OF THE NERVOUS SYSTEM. 11 

The eleventh thoracic nerve gives filaments to the posterior part of 
the diaphragm. 

The twelfth, described by Haller as the first lumbar nerve, anasto- 
moses by a large branch with the first lumbar pair, and sends filaments 
to the diaphragm, then passes before the superior part of the quadratus 
lumborum muscle, between it and the posterior tendon of the transver- 
salis, gives off filaments and divides at its external edge into superficial 
and deep abdominal branches. The former pass between the trans* 
versalis and obliquus interims abdominis muscles, and terminate there, 
and also in the lower part of the rectus and pyramidalis muscles. The 
second go between the two oblique muscles, pass through the external, 
and are distributed to the integuments of the abdomen as far as the 
ossa ilia. 



ARTICLE SECOND. 

LUMBAR AND SACRAL NERVES. 

§ 1813. The description of the lumbar and sacral(l) nerves ought 
to follow that of the thoracic, because by then describing the cervical, 
we proceed from below upward to the explanation of the encephalic 
nerves. We shall combine our observations in regard to these two 
orders of spinal nerves, because they resemble each other in their most 
essential characters, and particularly as they unite to form the nerves 
of the inferior extremities. 

The five lumbar nerves and the sacral nerves, which are also five 
and sometimes six in number, arise near each other from the inferior 
prominence of the spinal marrow. They emerge from the medullary 
canal the lumbar passing out through the intervertebral foramina, 
situated between the lumbar vertebrae as between the last one and the 
upper surface of the sacrum. The sacral nerves form the sacral 
foramina except the last, which passes between the sacrum and the 
first piece of the coccyx. Not only the anterior and posterior roots of 
each pair, but the different pairs themselves are closely united to each 
other from their origin to the ganglions formed by their posterior 
branches* but neither the first nor second communicate by inter- 
mediate filaments. The sacral nerves differ from all other spinal 
nerves by the situation of their ganglions, which do not anastomose 
when coming from the nerve, but in the channel of the vertebral 
column and are as much more distant from the sacral foramina the 
lower the origins of the nerves to which they belong, so that the an- 
terior and posterior roots of these last unite even within the medullary 
canal The trunks resulting from their union divide near their origin, 
and also within the vertebral canal, into anterior and posterior branches, 

(1) J.L.Fischer, Descriptio anaComica nervorum lumbalium, sacralium et extre- 
mitalum infcriorum, Leipsic, 1791. 



12 DESCRIPTIVE ANATOMY. 

which do not usually anastomose together in this canal, but emerge, 
the first through the anterior sacral foramina, the others through the 
posterior sacral foramina. The union of the anterior and posterior 
roots of the sacral nerves in the medullary canal, undoubtedly corres- 
ponds to the fusion of the false sacral vertebrae in a single bone, and 
it takes place after the same type so evident in the vascular system. 
Perhaps, also, it partially depends on the greater distance between the 
point from whence the nerves originate, and that whence they emerge. 
One circumstance favors this conjecture, viz. that the place where the 
posterior and anterior roots unite, is farther in the inferior nerves where 
the trunk is proportionally longer. But this circumstance also favors 
the opinion first proposed, since the inferior false sacral vertebrae unite 
also sooner than the superior. 

The anterior branches of these ten nerves which enlarge very much, 
form a plexus which may be called the femoral or crural plexus (plexus 
femoralis). This plexus, like the brachial and cervical, is produced by 
the increase and multiplication of the anastomoses between the anterior 
branches, which is in proportion to the increase of volume of the 
nerves, and which takes place in breadth, and from without inward, 
and in thickness or from behind forward. 

We may consider separately the superior and inferior parts of this 
plexus, the first as the lumbar ox lumbo-abdominal(l) plexus, the se- 
cond as the sacral or sciatic plexus, since from each of these two parts, 
which are formed, the first by the lumbar, the second by the sacral 
nerves, arise nerves which are distributed differently. Still as the 
principal nerves which come from it are all distributed to the lower 
extremities, it is more convenient to regard them as forming one plexus 
only, as the inferior lumbar nerves mostly form the sacral plexus and 
the nerves which come from it. 

This plexus is indicated in tho dorsal rp.ginn hy the much smaller 
anastomosis between the anterior branches, and which are constantly 
developed in the inferior thoracic pairs. 

Of the nerves which form it, the upper suddenly enlarge very much 
from above downward, and the lower from below upward. 

The last two sacral nerves are the smallest, and the last es- 
pecially is the smallest of all the spinal nerves. Next comes the first 
lumbar, then the third sacral ; the second lumbar is a little larger, 
being about the same size as the second sacral ; the third and fourth 
lumbar which are almost equal, are a little larger than the preceding. 
The fifth lumbar and the first sacral are much the largest. 

Dorsal branches which are much smaller arise fronfall these nerves 
which unite to form the crural plexus, commencing before the union of 
their anterior branches, when they emerge from the foramina : these 
go directly backward between the transverse processes of the lumbar 
vertebrae and the sacrum, passing there through the posterior sacral 

(1) J. A. Schmidt, De plexu lumbali, de nervis lumbaliqxis corumaue »/ej» ram 
mentarius anatomico-palhologicus, Vienna, 1794. l P u com ~ 



OF THE NERVOUS SYSTEM. 13 

foramina. These branches are distributed to the posterior part of the 
muscles of the back, to the gluteus rnaximua and the skin which 
covers them. 

The posterior branches, the dorsal or lumbar (R. postici, s. dorsales, 
s. lumbales), of the lumbar nNyes diminish considerably in volume from 
the first to the last, so that t!._ 'ast two rarely extend to the skin, but 
are distributed only in the comay. belly of the sacro-lumbalis and 
multifidus spinse muscles. From the first sacral nerve to the fourth, 
the posterior branches again enlarge much. That of the fourth is the 
largest ; the fifth is smaller, while the sixth is much more minute. 

§ 1814. The anterior or abdominal branches (R. antici, s. abdomi- 
nales) of the lumbar nerves pass behind the psoas magnus muscle, unite 
not only with each other, but beside the first with the anterior branch of 
the last dorsal, the last with the anterior branch of the first sacral, to 
form the lumbar plexus, the lumbar ganglion of the ganglionnary 
nerve, and produce the nerves we are about to describe. The anterior 
branches of the sacral nerves, principally the first, second, third, and 
fourth, concur in the same manner to form the sacral plexus to which 
the fifth contributes least, and the sixth takes no part when it exists. 

Some ramifications arise from the anterior twigs after their union, 
some of which, the smaller ones, are usually formed by the filaments 
of a single nerve, while others which are larger, arise from the union of 
fasciculi from several nerves. 

The first are principally the external pudic nerve, several branches 
for the muscles in the lumbar region, the skin of this region and the 
common integuments of the inguinal region, the gluteal nerves and the 
inferior and middle hemorrhoidal nerves. 

The second are the three nerves of the lower extremities, the obtu- 
rator, the crural, and the gluteal nerve. 



A. SMALL NERVES WHICH ARISE FROM THE ANTERIOR BRANCHES OF 
THE LUMBAR AND SACRAL NERVES. 

§ 1815. First and second lumbar nerve. From the first and second 
lumbar nerve, especially from the inferior extremity of the plexus be- 
tween them, arises the external pudic or the genitocrural nerve (JV. 
pudendus extemus, s. spermalicus extemus, s. inguinalis, s. genito-cru- 
ralis), which passes between the superior digitations of the psoas mus- 
cle, arives at the anterior face of this muscle, on which it goesfrom behind 
forward and from above downward, and divides within the pelvis into 
branches which all emerge from the inguinal ring. Among these, the 
most considerable which are always the continuation of the trunk, 
arrive at the spermatic vessels, and are distributed in the male in the 
cremaster muscle and its coats, and in the female in the round liga- 
ment of the uterus, and anastomosing with the inferior pudic nerves, 
terminate in the glands and integuments of the inguinal region. The 
external passes under the crural arch, penetrates the aponeurosis, is dis- 

Vol. III. 3 



14 DESCRIPTIVE ANATOMY, 

tributed in the skin to the middle of the internal face of the thigh, and 
anastomoses with some filaments n ft h A brutal nerve. 

Besides there arise from the first lumbar nerve and its anastomosis 
with the second, branches designed for the psoas, the quadratus lum- 
borum, and'the transversalis abdominis muscles, and for the integuments 
of the lumbar and inguinal regions. One of these branches, which is 
large, penetrates the psoas muscle, goes forward between the obliquus 
internus and transversalis along the crest of the ilium, and terminates 
in the inferior part of the large abdominal muscles and skin of this 
region and of the scrotum. 

Several filaments come from the second lumbar nerve and are 
distributed to the psoas and quadratus lumborum muscles and the skin 
of the lumbar and inguinal regions : usually there arise one or two 
distinct branches which are longer (nerfi lio-scrotal, Ch.), which passing 
through the psoas muscle, proceed outwardly before the quadratus 
lumborum, penetrate the transversalis, then the obliquus internus, to 
which they give filaments, go forward along the crest of the ilium, 
perforate the aponeurosis of the obliquus externus, and are distributed 
to the skin of the inguinal region and scrotum. 

3d. The third lumbar nerve usually gives off a cutaneous nerve 
which unites to the preceding one or replaces it either partially or 
wholly, descends between the psoas and iliacus muscles, emerges from 
the pelvis, passing under the outward extremity of the crural arch and 
is distributed to the external and anterior extremities of the integuments 
of the thigh to the neighborhood of the knee. There it is the infe- 
rior branch of the crural plexus of Bichat, the inguino-cutant of 
Chaussier. 

4th. The fourth lumbar nerve usually gives branches only to the 
iliacus muscle. 

5th. The anterior branches of the fourth and fifth lumbar nerve unite 
to form a very considerable trunk, the lombo-sacral nerve of Bichat 
(JV. lumbo-sacralis), which is much larger than the crural, and give 
origin in the very cavity of the small pelvis, but always before uniting 
with the first sacral nerve, to the superior gluteal nerve (JV. glutceus 
superior), which emerges from the pelvis below the upper edge of the 
sciatic notch, is distributed to the gluteus medius and minimus, and 
penetrates even forward to the tensor vaginae femoris. 

6th. From the second and third sacral nerve, come some fasciculi 
which unite then give filaments to the pyramidalis muscle, and coming 
from the pelvis below it, go to form the inferior gluteal nerve 

Before these fasciculi, a very considerable nerve arises from these 
same nerves farther below and forward, sometimes also from the fourth 
sacral nerve, called the external common hemorrhoidal nerve (JV. ««- 
dendo-hczmorrhoidahs communis externus), which re-enters into the 
pelvis between the two sacro-sciatic ligaments, and divides into two 
branches, the external pudtc, and the inferior hemorrhoidal nerve 

The external or superior pudic nerve, ischio-p&rien or ischdo-clitori 
dim, Oh. (N.pudendus externus, s. superior), goes along the ascending 



OP THE NERVOUS SYSTEM. 15 

branch of the ischium and the descending branch of the pubis, pro- 
ceeding on gives branches to the obturator internus and bulbo-caver- 
nosus muscles, then passes under the symphysis pubis to go forward, 
as the dorsal nerve of the penis (JV. dorsalis penis) in the male, and 
that of the nerve of the clitoris ( JV. clitorideus, s. pudendus superior) 
in the female, proceeds along the penis and clitoris, sends filaments to 
the skin which covers them, and also to the mons veneris and mucous 
membrane of the urethra, and terminates finally in the glans. 

The inferior hemorrhoidal nerve, called also the inferior pudic (JV. 
hcemorrhoideus, s. pudendus inferior), partly accompanies the pre- 
ceding, then goes upward between the bulbo- and ischio-cavernosus 
muscle, is distributed to the integuments and in all the muscles of the 
perineum to the inferior extremity of the rectum, the skin of the scro- 
tum and mucous membrane of the urethra, and anastomoses with the 
external pudic, the inguinal and internal hemorrhoidal nerves. 

From the difference in size between the penis and clitoris, the external 
pudic is the larger of these two branches in the male, while the internal 
hemorrhoidal is the larger in the female. 

7th. The third and the fourth sacral nerves also give off the middle 
hemorrhoidal nerves (JV. hcemorrhoidales medii), which are smaller, 
and not united at their origin ; but this term is not exact for they 
are distributed partly to the rectum, the levator and sphincter ani mus- 
cles, and proceed on the side of this intestine to be distributed from be- 
low upward in the walls of the bladder, at the commencement of the 
urethra, uterus, and vagina, the prostate gland and vesicular seminales 
in the male, and frequently anastomose with the lower part of the 
great sympathetic nerve to give origin to the hypogastric plexus. 

8th. The fifth and sixth lumbar nerves, when they exist, are in fact 
connected with the crural plexus, but do not contribute to form the 
nerves which come from them. Their anterior branches are distributed 
to the sacro-coccygeal, the levator, and sphincter ani muscles. Their 
posterior are distributed in the integuments of the posterior part of the 
anus and perineum. 



B. LARGE NERVES WHICH ARISE FROM THE ANTERIOR BRANCHES OF 
THE LUMBAR AND SACRAL NERVES, OR NERVES OF THE INFERIOR 
EXTREMITIES. 

I. OBTURATOR NERVE. 

§ 1816. The obturator nerve, sous-pubio-femoral, Ch. (JV. oblura- 
torius),(l) the smallest of those belonging to this division, arises from 
the most anterior fasciculi of the second, third, and fourth lumbar nerves, 
rarely from the first, by an equal and sometimes greater number of 

(1) See in regard to this and the following- nerve, M. C. Styx, Descript. anat. 
ncrvi cruralis et obturatorii, Jena 1782. 



16 DESCRIPTIVE ANATOMY. 

roots, which meet at acute angles. It descends into the lower pelvis, 
before the following nerve, is covered by the psoas muscle, goes for- 
ward along the linea innominata, accompanied by the vessels of the 
same name, comes out through the obturator foramen, and divides into 
two branches, an anterior superficial and large and a posterior deeper 

The anterior branch is distributed to the gracilis, the adductor longus, 
and brevis muscles, and sends to the internal saphena nerve some 
branches which are sometimes so large that this last seems to arise 
from it rather than from the crural. 

The posterior branch is distributed in the obturator muscles, particu- 
larly the externus, and in the adductor magnus muscle, even descend- 
ing to near its inferior extremity. 

II. CRURAL NERVE. 

§ 1817. The crural nerve, femoro-pi'ttibial, Ch. (JV. cruralis), is 
larger than the preceding, behind which it is situated, arises from the 
posterior part of the first, second, third, and fourth lumbar nerves, 
descends along the posterior and external side of the crural artery, be- 
tween the psoas and iliacus muscles, gives several branches to these 
two muscles, but principally to the second, and furnishes one conside- 
rable which sometimes come off higher than the branches destined 
to the iliacus muscle, anastomoses near the crural arch with another 
branch which arises in this place, comes sometimes also from the 
fourth lumbar nerve, and then is distributed in the integuments of the 
anterior and internal face of the thigh. This branch is called the 
superior or the small saphena nerve (JV. saphenus superior, s. minor). 

A branch is generally given off a little below the crural arch which 
proceeds from within outward, and goes to the common lower ex- 
tremity of the iliacus and psoas muscles. 

The nerve then divides generally below the crural arch into two 
branches, an external larger, and an internal smaller, above. 

The external branch also soon divides into several twigs, which go 
to the four heads of the extensor of the leg, to the crurceus, and to 
the tensor vaginal femoris muscle. These branches descend to the 
articulation of the knee and penetrate into its capsule. 

The internal branch gives to the sartorius muscle many twigs, most 
of which enter its middle and inferior part. It gives them also to the 
skin of the internal face of the thigh. But the largest of all the 
branches which come from it is the internal saphena nerve libio-cu- 
tane, Ch. (JV saphenus iniernus). This nerve accompanies the in 
ternal saphena vein, which it surrounds at several different parts 
distributes some filaments to the integuments of this region descends 
on the back of the foot, and extends even to the great toe. 



OF THE NERVOUS SYSTEM. 17 



III. SCIATIC NEIIVE. 



§ 1818. The sciatic nerve, grand femoro-poplite', Ch. (JV. ischiadi- 
cws),(l) the largest of all the nerves, not only of the inferior members, 
but even of the whole body, arises from the inferior half of the fourth 
lumbar nerve, and from all the fifth, also from the three superior sacral ; 
the anterior branches unite to form the sciatic or sacral plexus (plexus 
sacralis, s. ischiadicus), which is only the inferior part of the crural 
plexus, although we usually consider this the only plexus of nerves of 
the lower extremities. 

§ 1819. The sciatic nerve sometimes, partially or wholly, gives off 
the superior gluteal nerve and always the inferior either wholly or 
partially. This last emerges sometimes above and sometimes below 
the pyramidalis muscle, anastomoses with a branch of the sciatic 
nerve which arises a little lower, and is distributed with it in the 
gluteus maximus muscle. 

§ 1820. The sciatic nerve emerges from the sacral plexus through 
the sciatic notch, between the pyramidalis and gemelli muscles. 

There it sends to the obturator internus a considerable branch which 
penetrates from without inward between the large and small sciatic 
ligaments, and enters from below upward into this muscle. 

Then it gives a second, which descends before the gemelli and the 
tendon of the obturator internus, distributes filaments to the first two 
of these muscles, and is distributed in the quadratus femoris muscle. 

Still lower a large branch leaves its posterior part, and unites to the 
inferior gluteal nerve (§ 1788), with which it goes to the gluteus 
maximus muscle. 

The trunk first gives branches to the flexor muscles of the thigh ; 
then to the long head of the biceps ; then to the semitendinosus ; far- 
ther on, to the semimembranosus muscle ; finally, to the short head of 
the biceps. The filament of the semimembranosus is distributed also 
to the adductor magnus muscle. 

Farther on it gives off the middle posterior cutaneous nerve (JV. 
cutaneus posterior medius), which descends under the skin of the pos- 
terior face of the thigh and leg to the calf, and anastomoses with some 
filaments of the superior and inferior nerves. 

The inferior posterior cutaneous nerve (N. cutaneus posterior infe- 
rior) is given off below this branch ; it proceeds in part like the former 
one, and is partially expanded in the posterior part of the capsular liga- 
ment of the knee. 

§ 1821. The sciatic nerve then divides into two branches : the in- 
ternal, the larger, is the tibial nerve, and the external, the smaller, the 
peroneal nerve. This division usually takes place at the middle of the 
thigh, often higher up, and even above the sciatic tuberosity, so that 
the two branches are separated from each other by the pyramid- 
alis muscle. 

(1) J. H. Joerdcns, Dcscriptio ncrvi ischiadici, Erlangcn, 1788. 



18 DESCRIPTIVE ANATOMY. 

When the bifurcation occurs higher than usual, it is analogous to 
the arrangement of the sciatic nerve in the mammalia. 

Rosenmuller mentions a national difference in regard to the height 
of this division, viz. that the sciatic nerves divide very high in the 
inhabitants of the north of Europe, while in those of the south it bifur- 
cates very low not far from the ham.(l) We have not observed this 
difference. 

When the nerve divides high, the two branches are separated by the 
pyramidalis muscle, and they descend, the external behind, the internal 
before it. 

The popliteal nerve (JV. popliteus) rarely or never exists. (2) At 
most the name of the internal and the external popliteal nerve may be 
given to the upper part of the two terminating branches of the sciatic 
nerve, from their origin to the femoro-tibial articulation. 

a. Peroneal nerve. 

§ 1S22. The peroneal or external popliteal nerve (JV. peroneus) often 
gives origin to the posterior, inferior, and middle cutaneous nerves. It 
descends from within outward on the internal side of the biceps femo- 
ris muscle, passes between the extensor longus digitorum communis 
and peroneus longus muscles, sends filaments to these muscles, and 
likewise to the tibialis anticus, and divides very high up into two 
branches, the superficial and the deep peroneal nerves. 

§ 1823. The superficial peroneal, or the muscular cutaneous nerve, 
prttibio-digital, Ch. (JV. peroneus superjicialis), soon divides into two 
branches, an external superficial and small, the other internal, which 
is deeper and larger. 

The first, or the cutaneous peroneal nerve, which might more pro- 
perly be called the middle cutaneous nerve of the back of the foot, or the 
external branch of the peroneal nerve (JV. cutaneus peroneus, s. cuta- 
neus medius dorsi pedis, s. cutaneus peroneus externus), descends on the 
peroneus brevis muscle, passes on the crucial ligaments of the tarsus, 
is distributed to the skin of the external part of the back of the foot, and 
terminates by filaments which are the tibial nerve of the little tot, the 
dorsal nerves of the fourth toe, and the peroneal nerve of the third toe. 

The second, the anterior nerve of the back of the foot (JV. dorsi pedis 
anticus communis, s. peroneus anticus, s. pedalis anticus), is situated 
before the former, also near the surface, and is distributed partly to the 
internal half of the back of the foot, partly to the skin of the external 
and anterior faces of the leg," and terminates by producing the dorsal 
nerves of the two external toes and the peroneal nerve of the third. 

§ 1824. The deep peroneal or anterior tibial nerve, prdlibio-svs-plan- 
taire, Ch. (JV. peroneus profundus), descends deeply between the 

(1) In Ncer Journal dcr Erjlndungcn in der Natur-und Arzncywissentrhnft * 
ii., p. 100. <*<<najc, part 

(2) Coopmans has made the remark (Neurol., ed. 2, p. 198. 



OF THE NERVOUS SYSTEM. 19 

muscles on the anterior face of the tibia, at the side of the anterior 
tibial artery, but does not pasg with it from the posterior to the anterior 
face of the leg, between the two bones, for the whole trunk of the 
peroneal nerve is situated and divides on the external face of the fibula. 

Such at least is always the arrangement of the deep peroneal 
nerve according to our observations. Although we have made many 
careful dissections, yet we have never seen it pursue the course of the 
anterior tibial artery. Thus, although this authority is sanctioned by 
a great name,(l) it certainly is not the usual arrangement, and should 
be considered as a very rare anomaly, more especially as many 
writers, Coopmans(2) among others, do not sanction it, or speak only 
of the first. 

This nerve gives filaments to the peroneus longus, and to the 
extensor longus digitorum communis muscle, to the tibialis anticus, 
and to the extensor hallucis proprius, passes under the crucial liga- 
ment of the tarsus, and arrives on the back of the foot, where it termi- 
nates in the extensor digitorum brevis, the first interosseous muscle, and 
the internal part of the skin of this region, by anastomosing with some 
branches ofthe cutaneous nerve around the foot, so that the dorsal nerves 
of the large toe more properly arise from this than from the latter. 

We have alwaj^s found the peroneal nerve distributed in this man- 
ner, but we have never found that of the two branches into which it 
divides at the upper extremity of the fibula, one was the external cu- 
taneous nerve, the other, the common trunk of the anterior tibial and 
internal cutaneous nerves ;(3) Sabatier,(4) Coopmans,(5) andReil,(6) 
state the same distribution as ourselves : this arrangement then should 
be regarded as the most constant. 

b. Tibial nerve. 

§ 1825. The tibial or internal popliteal nerve (JV. tibialis), the 
largest and most internal of the two terminating branches of the sciatic 
nerve, may be called the popliteal (JV*. popliteus), from the bifurcation to 
the calf of the leg, although this term is not perfectly exact. It gives 
oft" first a considerable cutaneous nerve, the long posterior cutaneous 
nerve ofihefoot and the leg; or rather the external cutaneous tibial 
nerve of the foot (N.cutaneus longus posterior tibia}, s. cutaneus pedis 
externus, s. tibialis), which nevertheless often comes from the peroneal 
nerve, or at least especially when the sciatic nerve bifurcates high up, 
is partially replaced either by the posterior and inferior branch of this 
latter, or even by its inferior and middle cutaneous nerve. 

(1) fe'eemmerring-, Hirn-und Nervcnlchre, p. 312. 

(2) Ncurologia, p. 203. 

(3) Scernmerring, Nervcnlchre, p. 309. 

(4) TV. complct (Vanat. ed. 3. vol. iii. p. 328. 

(5) Ncurologia, p. 201, 203. 

(6) Anat. descript. vol. iii. p. 309. 



20 DESCRIPTIVE ANATOMY. 

The external cutaneous tibial nerve of the foot descends behind the 
muscles of the foot, goes outward below, the external malleolus, pro- 
ceeds along the external edge of the foot and the fibular edge of the 
fifth toe, constituting its dorsal peroneal nerve, and proceeds to the 
top of it. 

The tibial nerve then gives off a small branch to the posterior part 
of the capsule of the articulation of the knee. This branch is some- 
times given off higher or as high as the preceding. 

Farther on, the trunk of the tibial nerve gives external and internal 
branches to the three heads of the triceps, the plantaris, the poplitcus, 
the tibialis posticus, and the flexor hallucis longus. 

§ 1826. The tibial nerve then goes forward between the upper two 
heads of the triceps sur« muscle, descends between the tendo achillis, 
the tibialis posticus and the flexor hallucis longus, passes behind the 
malleolus intemus, and goes to the sole of the foot. 

Behind the malleolus it divides into three branches, one superficial 
and two deep. 

§ 1827. The superficial branch or the external tibial nerve (JV. 
tibialis exterior), more properly the proper cutaneous plantar nerve 
( JV. cutaneus plantaris propritts), is distributed to the skin below the 
malleolus internus, and at the posterior part of the sole of the foot. 

§ 1828. The two deep branches are the internal and the external 
plantar nerve. 

The internal plantar nerve ( JV. plantaris internus) is usually a little 
larger and more superficial than the other ; it goes forward under the 
long head of the adductor hallucis, between it and the flexor communis 
digitorum brevis, and divides far back into two branches, an internal 
and an external: the latter is the larger. 

The internal branch having given filaments to the adductor hallucis, 
becomes the first plantar nerve of the toes (N. digitorum plantaris 
primus), the tibio-plantar nerve or the internal nerve of the great toe 
(JV. plantaris internus, s. tibialis hallucis). 

The external branch also subdivides into two others, the external of 
which is also the larger. 

The internal or the third plantar nerve of the toes also divides into 
the external plantar nerve of the second toe, and the internal plantar 
nerve of the third toe. 

The external or the fourth plantar nerve of the toes divides into 
the external plantar nerve of the third toe, and the internal plantar 
nerve of the fourth. 

Thus this trunk distributes its branches to the internal half of the 
skin of the foot, to the two sides of the three internal toes, and to the 
internal side of the fourth. 

§ 1829. The external plantar nerve (JV. plantaris cxternus) goes 
forward and outward between the flexor communis digitorum brevis 
and the tendon of the flexor longus, and divides before the tuberosity 
of the calcaneum into three branches, ' '^ 



OF THE NERVOUS SYSTEM. 21 

The internal branch, the fifth plantar nerve of the toes, which is en- 
tirely cutaneous, goes forward to the anterior extremity of the tarsus, 
where it divides into the plantar nerve of the fourth toe, and the in- 
ternal plantar nerve of the fifth. 

The external branch, the musculo-cutaneous nerve, goes forward 
along the fibular edge of the sole of the foot, gives filaments to the 
abductor minimi digiti muscle, and becoming the external plantar 
nerve of the fifth toe, advances to its extremity, where as in the great 
toe, it receives at its external edge a distinct branch, an arrangement 
which is worthy of notice, as it contributes to the lateral symmetry. 

This nerve forms the sixth plantar nerve of the toes. 

The middle, deep, or muscular trunk is the largest. It goes ob- 
liquely inward and forward, penetrates between the tendons of the 
extensor longus digitorum communis and the deep muscles of the sole 
of the foot, and distributes itself in the lumbricales, the adductor and 
flexor hallucis muscles, and in almost all the internal part of the 
interossei muscles, and the small muscles of the fifth toe. 



ARTICLE THIRD. 

OF THE CERVICAL NERVES. 

§ 1830. Till the time of Willis, eight cervical nerves, tracheliens 
Ch. (JV. cervicales, s. JV. colli)(l) were admitted, but this anatomist 
and many after him, have mentioned only seven : as they consider the 
first cervical as the last encephalic nerve, an opinion less correct than 
the ancient. The general characters of these eight nerves are : 

1st. Of all the spinal nerves they have the least extent in the verte- 
bral column from their origin to the place where they penetrate the 
dura-mater, and emerge through the intervertebral foramina. 

2d. The internal extremities of their roots are closer to each other 
than those of the thoracic nerves, but farther than those of the lumbar 
and sacral nerves. 

3d. The different pairs are united together by anastomoses ; these 
are usually simple, and extend from the inferior edge of the root of the 
superior nerve, to the upper edge of that of the lower nerve, and form 
the upper part of this last. The anastomosing filaments of the posterior 
roots are more constant than those of the anterior ; the latter usually 
exist only between the second and third pairs, and the third and fourth, 
and are deficient between all the others. On the contrary, the anas- 
tomosing filaments of the anterior roots exist in almost every part, but 
are sometimes deficient between the lower pairs. They are very 
seldom met with between the last cervical and the first dorsal nerve. 

We, however, should observe that the anastomosing filaments often 
do not exist between the middle cervical pairs, although found between 
the superior and the inferior nerves. 

(1) J. Bang, Nervorum cerviealium analomc ; in Ludwig, Se. neur. 
Vol. III. 4 



22 DESCRIPTIVE ANATOMY. 

The arrangement of these filaments is not always exactly the 
same ; we usually see a filament which goes a little obliquely upward 
and outward from the internal extremity of the upper edge of the 
lower nerve, towards the external extremity of the lower edge of the 
upper nerve. But sometimes this filament descends directly from the 
lower edge of the upper nerve, to the upper edge of the lower nerve. 

Between this arrangement and the preceding is one which is inter- 
mediate, where the most superior fasciculus of the lower nerve divides 
at its centre into two parts, the upper of which goes to the upper 
nerve in the first of the two modes mentioned above, while the lower 
proceeds in the direction of the fasciculus, forming the most upper part 
of the lower nerve. Sometimes one or two thin fasciculi are found 
between two pairs of nerves, and usually a little nearer the lower than 
the upper. When there is only one fasciculus, this divides into two ; 
when two, they arise immediately one at the side of the other. In 
both cases either the fasciculi primitively distinct, or the two branches 
of the single fasciculus separate from below upward immediately after 
arising, and form, one the most inferior fasciculus, the other the most 
superior of the pairs between which they are situated. Sometimes 
they are united together by superior and inferior fasciculi, and after- 
ward by a transverse filament. 

The first arrangement usually exists between the inferior cervical 
nerves, the third between the middle, the second between the superior, 
and the fourth between the first two, counting from above downward. 

The cervical nerves may be divided into tw r o groups ; the first com- 
prises the four lower pairs, the other the four upper pairs, for the first 
differ much from the second, as they enlarge to give origin to the nerves 
of the upper extremities. 

A. INFERIOR CERVICAL NERVES AND FIRST DORSAL NERVE, OR NERVES 
OF THE UPPER EXTREMITIES. 

§ 1831. The nerves of the upper extremities (JV. brachiales, s. ex- 
tremitath superior!*) (I) arise from the first dorsal and the four in- 
ferior cervical nerves, which unite at some distance from their foramina 
to form the brachial plexus, so that a greater number of trunks comes 
afterward from the latter, each of which is formed from the fasciculi 
coming from several of the carrying nerves. The first dorsal nerve 
emerges below the first dorsal vertebra, the eighth cervical below the 
seventh cervical vertebra, the seventh below the sixth, the sixth below 
the fifth, and the fifth below the fourth. That nerve which usually 
occupies the centre of the group, that is the seventh cervical nerve is 
the largest : the first dorsal and the fifth cervical nerves are the 
smallest : the fifth cervical nerve is smaller than the first dorsal and 
the sixth and eighth dorsal are about the same size. ' 

(1) J. J. Klint, De ncrvis brachii, Gottiagen .1784.— P. Carrmer n*™ , 
pathol. t li. Amsterdam, 1760. tamper, Dcmonst. anal. 



OF THE NERVOUS SYSTEM. 23 

The nerves which usually emerge from the brachial plexus are the 
thoracic, the scapular, the axillary, the radial, the external cutaneous, 
the median, the ulnar, and the internal cutaneous nerves. 

§ 1832. Before uniting, the five nerves which form the brachial 
plexus give off much smaller posterior branches, which go to the deep 
dorsal muscles of this region. The brachial nerves are then only the 
enlarged anterior branches of the superior dorsal and the four inferior 
cervical nerves. 

§ 1833. These anterior branches descend from within outward, pass 
between the scalenus amicus and medius muscles, and soon unite to 
form the brachial plexus (plexus brachialis).(l) The two superior and 
two inferior usually unite before the middle with the adjacent branches. 

The fifth and the sixth usually unite the first. 

Two nerves arise from their union. 

The superior after passing several inches divides into two branches, 
one of which is the axillary or circumflex nerve, the other is large and 
unites with the large posterior fasciculi of the seventh and eighth cer- 
vical nerves to form the radial nerve. 

The inferior, having proceeded two or three inches, unites with one 
or two anterior fasciculi of the seventh cervical nerve, and thus pro- 
duces a more or less complicated plexus," whence the external cu- 
taneous or the musculo-cutaneous nerve wholly, and the median par- 
tially arise. 

The seventh cervical nerve divides two or three inches from its 
emerging from the spinal canal into an anterior and a posterior branch, 
of which the second is larger. 

The posterior branch blends with the upper posterior branch of the 
eighth cervical nerve in a small trunk, which soon joins the posterior 
branch of the trunk formed by the union of the fifth and sixth cervical 
nerves, and gives origin to the radial nerve. 

From the anterior branch and the common trunk formed by the 
union of the fifth and sixth cervical nerves, several anterior thoracic 
nerves arise and then the musculo-cutaneous nerve ; it gives rise with 
the eighth cervical and the first dorsal nerves to the median nerve. 

The eighth cervical nerve divides into two branches, one posterior, 
thinner but longer, the other anterior, shorter but much thicker. 

The posterior unites to some branches of the fifth, sixth, and seventh 
cervical nerves to form the radial nerve. 

The anterior joins the first dorsal nerve. 

The common trunk formed by this last union, divides into two 
branches, a superior and an inferior. 

The superior, united with the fasciculi of the fifth, sixth, and seventh 
cervical nerves, becomes the median nerve. 

The inferior forms the ulnar nerve. 

The first dorsal nerve divides into two other branches, both of which 
unite with the eighth cervical nerve. 

Prochaska De struct, nerv., 



(l)Ba.n<r(loc. ctt.) has figured the brachial plexus— Proc 
ienna, 1779, tab. iv. v.— Scarpa, Annot. anat., B. 1. lab. fi 



Vienna, 



24 DESCRIPTIVE ANATOMY. 

The superior assists to produce the radial nerve. 
The inferior concurs to form the ulnar nerve, and sometimes alone 
produces the internal cutaneous nerve. 

I. THORACIC NERVES. 

§ 1834. The thoracic nerves, stcrno-thoraciques, Ch. (JV. thoracici) 
may be distinguished into posterior and anterior. 

The posterior arise from the branches of the fifth and sixth, some- 
times also from the seventh cervical nerve, which are mostly united in 
a nerve which descends on the external face of the serratus major 
muscle, and is distributed in that muscle. 

The anterior arise from the anterior trunk formed by the union of 
the fifth and sixth cervical nerves, and also from the anterior branch of 
the seventh and eighth, descend from behind forward, and give filaments 
to the subclavius, the pectoraiis major and minor muscles, the thymous 
gland, and the skin of the anterior and superior part of the chest and 
shoulder, where they anastomose with some filaments of the fourth 
cervical and axillary nerves. 

II. SCAPULAR NSBVE. 

§ 1835. The scapular nerve (N. scapularis), which is rather large 
often comes from the fifth cervical nerve before it joins with the follow- 
ing. When it arises only after the union, it commences almost in the 
place where it is, passes through the coracoid notch of the scapula, 
arrives thus on the posterior face of the scapula, sends filaments to the 
supraspinatus muscle, goes downward over the neck of the scapula, 
and arrives at the infraspinal fossa, where it is distributed to the 
infraspinatus and teres minor muscles. 

III. AXILLARY NERVE. 

_ § 1836. The axillary nerve, scapulo-humeral, Ch. (JV. axillaris, s. 
circumflexus brachii), or more properly the circumflex nerve, arises 
from the posterior and superior branch coming from the division of the 

n^° n t U f /° rrae , d ? y the Uni0n of the fifth a » d ^xth cervical 
often rer P If' 1 br f ch <* to the infraspinatus muscle, which 

then ZZ me ST* ^ ^ T° n tmnk mentl0ned * bove > & 
men gives some to the teres minor and major muscles then na^inp- 

cervical nerve send, filaments to the in.egLems if thlreAon 



OF THE NERVOUS SYSTEM. 25 



IV. RADIAL NERVE. 



§ 1837. The radial nerve, radio-digital, Ch. (JV. radialis), is much 
larger than the preceding, arises from fasciculi of all the brachial nerves 
by three branches, which come one from the seventh cervical nerve 
only, the second from the fifth and sixth, and the third from the eighth 
cervical and the first, dorsal nerves. Soon after its origin, it gives a 
large branch to the latissimus dorsi and filaments to the triceps ex- 
tensor muscles. A little below the middle of the arm it turns on the 
humerus, often reappearing on its anterior face between the brachialis 
internus and the supinator longus muscles. 

In turning on the humerus it gives a long and thin cutaneous 
branch, the superior external cutaneous nerve (JV. cutaneus externus 
superior). This nerve descends along the radial edge and the inner 
face of the fore-arm, and interlaces with the cutaneous branch of the 
musculo-cutaneous nerve, extends a greater or less distance to the 
middle of the fore-arm, to the carpus, and even the thumb. 

The trunk of the radial nerve then gives branches to the supinator 
longus and the extensor carpi longus radialis muscles. It divides at 
the lower extremity of the fore-arm into two branches, a superficial or 
cutaneous and a deep or muscular. 

The superficial branch (R. superficialis dorsalis, s. cutaneus) de- 
scends along the anterior edge of the radius between the supinator 
longus and the radiales muscles, arrives at the outer face of the fore- 
arm, passing below the tendons of the first of these three muscles, and 
divides usually some inches below the inferior extremity of the fore-arm 
into two almost equal branches, the anterior being a little the larger, 
which distribute filaments to the anterior region of the integuments 
of the back of the hand, and to the dorsal face of the three anterior 
fingers. 

The anterior branch anastomoses in several places with' those of the 
cutaneous branch of the musculo-cutaneous nerve, sends filaments to 
the skin of the radial side of the carpus and metacarpus, and divides 
on the carpus into two small branches, the dorsal nerves of the thumb 
(JV. cutanei pollicis dorsales), which descend on its dorsal side along 
the radial and ulnar edges to its anterior extremity, furnish filaments 
to its dorsal face, and anastomose together and with the palmar nerves 
of the thumb. 

The posterior branch usually divides soon after arising into two 
principal ramuscules, an anterior and posterior. 

The anterior goes to the skin between the thumb and index finger, 
and arrived at the radial side of the last finger becomes the radio- 
dorsal nerve of the index finger (JV. dorsalis radialis indicus). 

The posterior soon subdivides into two filaments, one of which pro- 
duces the cubito-dorsal nerve of the index finger and the radio-dorsal 
nerve of the middle finger, while the second is the cubito-dorsal nerve 
of the middle finger. 



26 DESCRIPTIVE ANATOMY. 

All these ramifications frequently anastomose with each other or 
with those of the ulnar nerve, and thus give rise to a plexus called the 
dorsal arch of the hand (rete, s. arcus dorsalis mamis). 

The deeper or larger muscular branch gives off branches for the ra- 
dialis brevis and the supinator brevis muscles ; it then turns over these 
muscles and engages itself between their fibres, penetrates between 
the extensor digitorum communis muscle, arrives at the posterior sur- 
face of the fore-arm, gives off some large branches, some of which are 
recurrent to the extensor digitorum communis, to the extensor minimi 
digiti, and to the ulnaris internus and externus muscles. Then as the 
external interosseus nerve ( N. interosseous externus), it descends on the 
extensor and the adductor pollicis longus muscles, to which it sends 
filaments, as also to the extensor indicis proprius muscle, and is finally 
lost in the capsule of the wrist-joint. 

V. EXTERNAL CUTANEOUS NERVE. 

§ 1838. The external cutaneous nerve, or muscido-cutaneous nerve, 
or the perforating nerve of Casserius, radio-cutane', Ch. (JV. culuneus 
externus, s. musculo-cutaneus, s. perforans Casserii), is much smaller 
than the preceding, although it descends almost as low as it. It arises 
from the fasciculi of the fifth, sixth, and seventh cervical nerves. It 
sometimes comes from the median nerve. 

It frequently but not always penetrates the coraco-brachialis muscle. 
When this is not the case, it passes on the internal edge of this muscle, 
being joined to it only at its surface. It divides high up in the arm 
into two branches, the one muscular and small, the other cutaneous 
and larger. 

The muscular branch gives filaments to the coraco-brachialis 
muscle, to the two heads of the biceps, and to the brachialis internus 
muscle. 

The cutaneous branch passing between the biceps and the brachialis 
internus muscle, arrives at the anterior edge of the arm, descends on the 
radial side in the aponeurosis,' accompanying the cephalic vein. It anas- 
tomoses frequently above with the external cutaneous nerve, and below 
with the dorsal branch of the radial nerve ; it is distributed to the skin 
of the posterior surface of the fore-arm and the hand, and terminates at 
the thumb. 



VI. MEDIAN NERVE. 

§ 1839. The median nerve, medio-digilal, Ch. (JV. medianus), the 
largest nerve of the upper extremity, comes also from the brachial 
plexus. It descends on the inside of the arm near its lower extremity 
without giving off any branch, unless it be sometimes the external 
cutaneous nerve. 



OF THE NERVOUS SYSTEM. 27 

Some inches below the elbow-joint it gives several small muscular 
branches to the pronator teres, to the upper part of the radialis interims, 
the palmans longus, and to the upper part of the flexor digitorum brevis 
muscles. Near the elbow it gives off a considerable branch, the inter- 
nal tnterrosseus nerve ( JV. interrosseus internus), which descends before 
the flexor communis digitorum profundus, distributes branches to this 
muscle and to the flexor pollicis longus, is reflected on the anterior 
edge of the pronator quadratus, arrived thus at the posterior face of the 
fore-arm, it terminates in this muscle. 

The trunk descends before the flexor digitorum profundus, between 
the bones of the fore-arm, gives off filaments to this muscle and to the 
palmaris longus, and gives a cutaneous branch which is distributed in 
the integuments of the palmar face of the carpus, where it anasto- 
moses with the branches of the musculo-cutaneous nerve and the ulnar 
nerve. It then divides near the lower third of the fore-arm into two 
branches, an anterior or radial and a posterior or ulnar ; the first is the 
larger. 

These branches descend without giving any twig to the fore-arm 
between the tendons of the flexors, with which they pass under the 
ligaments of the carpus, where they usually unite by some transverse 
fibres. At the palm of the hand they separate. 

The radial branch divides at the carpus into an anterior and posterior 
twig. 

The anterior very soon divides into three filaments, the radio-palmar 
and the cubito-pahnar nerves of the thumb, and the radio-palmar nerve of 
the index finger , these frequently anastomose together, extend to the 
extremities of these two fingers, and terminate by considerable 
branches, and give filaments to the first lumbricalis muscle. 

The posterior then sends a large branch to the adductor brevis, to 
its opponens muscle and the flexor pollicis brevis, after which it be- 
comes the cubito-pahnar nerve of the index finger. 

§ 1840. The cubital branch divides at the commencement of the 
carpus into two twigs. 

The anterior which is smaller sends filaments to the second lum- 
bricalis muscle, and becomes the radio-palmar nerve of the third finger. 

The posterior which is larger sends filaments to the integuments of 
the hand, soon divides into two ramuscules, the cubito-pahnar nerve of 
the third finger and the radio-palmar nerve of the fourth. 



VII. ULNAR OH CUBITAL NERVE. 

§ 1841. The ulnar nerve, cubito-digital (JV*. ulnaris. s. cubilalis), is 
a little smaller than the preceding, and arises from the three inferior 
nerves of the brachial plexus. It descends inward and backward, gives 
off no branches along the arm except sometimes the internal cutaneous 
rerve, and arrives at the ulnar side of the fore-arm, passing imme- 



28 DESCRIPTIVE ANATOMY. 

diately behind the internal condyle of the humerus, where it may be 
easily compressed. 

Arrived at the fore-arm, it first gives off ramifications to the flexor 
digitorum profundus and to the flexor carpi ulnaris, and then sends 
under the skin along the basilic vein a small branch, called the long 
palmar nerve (JV*. ulnaris longus palmaris), which anastomoses in the 
carpus with an analogous branch coming from the median nerve ; 
about the middle of the fore-arm, it divides into two branches, a dorsal 
and a palmar. 

The dorsal branch (JV*. ulnaris dorsalis) passes between the ulna 
and the tendon of the flexor carpi ulnaris muscle, comes on the back 
of the fore-arm, where it subdivides into two twigs. 

The posterior or ulnar supplies the skin of the ulnar side of the hand, 
and becomes the cubito-dorsal nerve, of the fifth finger . 

The anterior or the radial also soon divides into two principal fila- 
ments, one of which is the radio-dorsal nerve of the fifth finger and the 
cubito-dorsal nerve of the fourth, the other is the radio-dorsal nerve of 
the fourth finger. 

This dorsal branch is distributed like the dorsal branch of the radial 
nerve. 

The palmar branch (JV*. ulnaris palmaris) which is larger, descends 
between the tendons of the ulnaris internus and the flexor digitorum 
communis muscles, and divides on the ulnar edge of the carpus into a 
superficial and a deep twig. 

The deep or muscular twig goes downward and forward between 
the adductor and flexor minimi digiti muscles, passes across to the 
radial side of the hand, going between the tendons of the flexor com- 
munis and interossei muscles, and sends numerous twigs to the mus- 
cles of the little finger, to the interossei and lumbricales, and to the 
adductor pollicis muscles. 

The superficial or cutaneous branch is smaller than the preceding, 
anastomoses by one or several filaments with the cubito-palmar branch 
of the median nerve (from this union we have a superficial palmar 
arch), and soon divides into two filaments, an anterior and a posterior. 

The anterior soon divides into the cubito-palmar nerve of the fifth 
finger and the common trunk of the cubito-palmar nerve of the fourth, 
and the radio palmar nerve of the fifth. 

Each finger receives two palmar and two dorsal branches, the first 
of which are the largest. They proceed along the radial and ulnar edges 
of the finger directly at the side of the digito-palmar artery, more in- 
ward and downward than it, that is, nearer the palmar face, as like- 
wise the superficial palmar arch is nearer the surface than their trunk. 
They go to the extremity of the fingers. In this passage they give 
off several large branches, distribute some small twigs to the palmar 
face of the finger, when they anastomose with each other. 



OF THE NERVOUS SYSTEM. 29 



VIII. INTERNAL CUTANEOUS NERVE. 



§ 1842. The internal cuiuneous nerve, cubito-cutane, Ch. (JV*. cu- 
taneus internus), usually arises from the first dorsal by several roots ; 
it sometimes though rarely comes from the ulnar, being the first branch. 
It descends directly below the skin at the side of the basilic vein in the 
arm. From its upper part arises the superior cutaneous nerve (JV*. 
cutaneus internus superior), which sometimes comes from the ulnar 
nerve, and is distributed to the triceps extensor muscle and the skin 
which covers it. A little lower it gives off the inferior internal cutaneous 
nerve (JV. cutaneus internus inferior), which distributes its branches to 
the lower part of the triceps extensor muscle, to the skin of the elbow, 
to the integuments of the ulnar edge of the fore-arm, and to the carpus, 
and which terminates on the cubital edge of the hand and little finger, 
descending along the basilic vein, and anastomosing with the branches 
of the ulnar nerve, which it meets in its course. 

In the whole course of this nerve its different branches anastomose 
frequently with each other and with those of the external cutaneous 
nerve on the posterior side of the fore-arm. 



B. SUPERIOR CERVICAL NERVES. 

§ 1843. The four superior cervical nerves are smaller than the 
inferior. Like the latter their size increases progressively from above 
downward, so that the second and third are the largest. They form 
with the lower ones an uninterrupted series ; and like them their an- 
terior branches immediately after their trunks have come from the 
intervertebral foramina, give off twigs which anastomose with the 
adjacent branches and form the cervical plexus, trachelo-sous-cutani, 
Ch. {plexus cervicalis). This plexus descends along the corresponding 
vertebrae, below the sterno-cleido-mastoideus muscle, outside of the in- 
ternal jugular vein, carotid artery, and pneumogastric nerve, on the 
scalenus posticus muscle. It anastomoses below with the brachial 
plexus, within with the superior and middle cervical ganglions of the 
great sympathetic nerve. "We have as much reason to think the dif- 
ferent branches of the cervical nerves are derived from them as that 
they arise from the cervical pairs themselves. 

Some modern anatomists, among whom are Bichat(l) and Clo- 
quet,(2) have adopted this method, and describe separately only the 
posterior branches and the commencement of the anterior, and consider 
the cervical plexus as the origin of all the nerves which arise after the 
union of the anterior branches. But we shall not follow them, as the 

(1) Anal. descripL, vol. iii. p. 234-246. 

(2) Tr. d'anat., vol. ii. p. 633-641. 

Vol. Ill 5 



30 DESCRIPTIVE ANATOMY. 

nerves of which they treat seem to arise from some particular pairs 
which are not seen in the other plexiform nerves of the spinal marrow. 
The diaphragmatic nerve is the only one to be considered sepa- 
rately, because produced not only by several pairs of the cervical 
plexus but also of the brachial plexus, so that it seems to belong in 
common to the superior and inferior section of the cervical nerves. 



I. DIAPHRAGMATIC NERVE. 

§ 1844. The diaphragmatic or phrenic nerve (JV. diaphragmati- 
cus, s. phrenicus)(l) arises by several branches from the lower extre- 
mity of the brachial plexus. The largest branch is always furnished 
by the anterior branch of the fourth pair, but a smaller one always 
arises from the third and often from the second, and about three from 
the brachial plexus. This nerve sometimes joins the ascending branch 
of the hypoglossal nerve. 

The diaphragmatic nerve descends on the side of the neck between 
the rectus capitis anticus and the scalenus muscle, gives branches to 
these muscles and to the thymous gland,anastomoses by a few filaments 
with the inferior and middle cervical ganglions of the great sympa- 
thetic nerve, enters the chest between the subclavian artery and vein, 
then goes forward, descends before the pulmonary vessels, and lastly 
passes between the internal wall of the external sac of the pleura and 
the pericardium, applied very exactly to the surface of this last mem- 
brane, and is finally distributed to the diaphragm. A little before 
arriving at this muscle, it divides into several branches which are 
united by intermediate filaments, some of which go to the convex face 
of the diaphragm and others pass through its costal portion and its 
central tendon, accompany the ascending vena-cava on the right, with 
which they emerge through the foramen quadratum, come into the 
abdomen, where they not only expand on the inferior face of the mus- 
cle, but also anastomose by several filaments with the solar plexus of 
the great sympathetic and with the gastric branch of the pneumo-gas- 
tric nerve. These anastomotic filaments almost always project at in- 
tervals, and these projections often form real ganglions. 

The left diaphragmatic nerve is situated farther back, and is longer 
than the right, as it turns around on the summit of the heart Be- 
sides the filaments it gives to the diaphragm, it sends some also to the 
lower part of the esophagus. 

(1) Kruger, De ncrvo phrenico, Leipsic, 1758. 



OF THE NERVOUS SYSTEM. 31 



II. FOURTH CERVICAL NERVE. 



§ 1845. The fourth cervical nerve(l) is a little smaller than the two 
adjacent. It emerges through the third intervertebral foramen, be- 
tween the anterior and posterior intertransversarii muscles, and imme- 
diately divides into an anterior and a posterior branch. 

The posterior is the smaller and deeper : it anastomoses with a 
branch of the third cervical nerve, gives a twig to the complexus 
muscle, passes transversely between this muscle and the semispinalis 
colli, to which also it sends large filaments, also to the multifidus 
spinae, then penetrates between the complexus and trapezius muscles, 
and expands in the corresponding skin of the neck. 

The anterior branch, which is the larger, first gives off a filament 
to the rectus capitis major anticus muscle : then it sends one of anas- 
tomosis to the cervical portion of the great sympathetic nerve, or to its 
superior cervical ganglion. It usually gives off also a twig to the 
descending branch of the hypoglossal nerve, and constantly sends fila- 
ments to the levator anguli scapulae muscle. 

It then sends an ascending anastomotic twig to the anterior branch 
of the third cervical, and forms with it the third cervical nervous plexus, 
then divides into three or four twigs which also proceed from above 
downward, and are called the supraclavicular nerves (JV. supra-clavi- 
culares). The latter are distributed principally to the skin which 
covers the clavicle and the shoulder. 

The anterior (JV. supra-claviculares anteriores) are distributed to the 
skin which covers the first piece of the sternum and the sternal ex- 
tremity of the clavicle to the mamma, anastomose with the anterior 
thoracic nerves coming from the fifth cervical, and send filaments also 
to the subclavius muscle. 

The middle (JV supra-claviculares medii) are distributed to the tra- 
pezius muscle and the posterior belly of the omo-hyoideus muscle, and 
also to the skin which covers the body of the clavicle, its scapular 
extremity, and the scapula. 

The posterior (JV supra-claviculares posterior es) go to the skin of 
the neck and of the shoulder. 

A small ascending branch generally arises from the anterior or 
the middle nerve ; this forms a very broad plexus by anastomosing 
with the middle subcutaneous cervical nerve, which comes from the 
third pair. 

The middle and the posterior anastomose with the accessory nerve 
partly in the skin, and partly in the trapezius muscle. 

(1) G. F. Peipers, Diss, sistens tertii et quarti nervorum cervicalium descrip- 
tionem, cui accedit succincta eorundem nervorum quinti, nervi phrenici, preesertim 
ratione originis nervi duri ejusque prcesertim rami inferioris, nervi hypoglossi et 
occipitalis maximi a secundo cervicalium nervo adumbratio, Halle, 1793. 



32 DESCRIPTIVE ANATOMY. 



III. THIBD CERVICAL NERVE. 



§ 1846. The third cervical nerve(\) is larger than the preceding. 
It emerges from the spinal canal between the second and the third 
cervical vertebra;, and divides into two branches, a posterior and an 
anterior. 

The posterior branch is much smaller than the anterior ; it proceeds 
from before backward between the anterior and posterior intertrans- 
versarii muscles, gives filaments to these two muscles and also to the 
transvcrsalis colli and the complexus minor muscles, goes backward 
passing on this latter, sends anastomosing filaments to the posterior 
branch of the second and third cervical nerves, and also to the small 
occipital nerve which comes from the anterior branch of the third pair, 
glides below the biventer cervicis nucha? and the complexus major 
muscles, which receive considerable filaments from it, and goes directly 
to the trapezius muscle in which it is distributed, and also in the middle 
region of the skin of the neck. 

The anterior branch sends first small twigs to the rectus capitis 
major anticus and to the longus colli muscles, then proceeds from above 
downward and divides into two branches, a descending and an as- 
cending. 

The descending branch, the superficial cervical nerve, the 
submental nerve, Ch. (N. superficialis colli, s. profundus, N. sub-cu- 
taneus colli medius) turns on the posterior edge of the sterno- 
cleido-mastoideus muscle, to go to the outer face of this muscle, to 
which it gives filaments, sends others which anastomose with the 
ascending branch, and terminates first, by descending ramifications 
called the middle and inferior subcutaneous cervical nerves (A*, subcu- 
tanei colli medii et inferiores), in the middle and lower part of the skin 
of the neck ; second, by ascending twigs which anastomose fiequenthy, 
both with each other and with the final twigs of the facial nerve in the 
skin which covers the ascending and horizontal branches of the lower 
jaw from the lobe of the ear to the chin, and thus form the superior 
subcutaneous cervical nerves (N. subcutanei colli superiores). 

The highestand most posterior portion of this descending branch, or 
ihe great auricular nerve, the zygomato-auricular nerve, Ch. (JV. 
auricularis magmis, s. cervicalis), goes directly upward, and passing 
behind the ascending branch of the lower jaw arrives at the exter- 
nal ear. Its ramifications are distributed from behind forward and 
from below upward in the integuments and posterior muscles of the 
external ear, and also in the skin of the auditory foramen 

The ascending branch <roes backward and upward, gives off first an 
ascending anastomosing filament which unites to a descending filament 
of the third pair to form the second cervical nervous plexus and often 
sends off immediately the great auricular nerve. In this case its pos- 



■tfme 



(1) Peipers, loc. cit.— Vic-d'Azyr, Memoiri sur Irs nrrfs <lc la scconrlr n ,/„ / * ■ 
me paire ccrvicale ; in the Mim. dc Paris, 1777, p. 21-10. scconde ei de la troi- 



OP THE NERVOUS SYSTEM. 33 

terior part, and when the great auricular nerve comes from the de- 
scending branch, its entire trunk becomes the small or the anterior 
occipital nerve ( JV occipitalis minor, s. anterior), which most generally 
soon divides into several filaments, ascends on the complexus minor 
and splenius capitis muscles and expands in the skin of the occiput, 
in that of the mastoid process, in that of the posterior and superior part 
of the external ear between the superior and posterior auricular 
muscles, farther forward than the large occipital nerve given off by the 
second cervical pair, although anastomosing frequently with this latter, 
as with the filaments of the facial nerve. 

IV. SECOND CERVICAL NERVE. 

§ 1847. The second cervical nerve(l) emerges from the spinal canal 
between the first and second cervical vertebrae. It is larger than the 
third, and divides into an anterior and a posterior branch, directly below 
the ganglion. 

The posterior branch, the great occipital nerve (JV*. occipitalis maxi- 
mus), is much larger than the anterior, which is contrary to the ar- 
rangement of the inferior cervical nerves except the first, and to that 
of all the other spinal nerves. It goes directly backward below the 
complexus minor muscle, first sends filaments to the obliquus capitis 
inferior muscle, gives off others which pass on this muscle to anasto- 
mose with the first and third cervical nerves, also gives them to the 
upper part of the two splenii muscles, to the biventer cervicis, the 
complexus and trapezius muscles under which it proceeds, to the mul- 
tifidus spinae and to the skin of the neck, approaches the median line, 
and arrives at the occipital bone ; it there forms most of the nerves in 
this region, ramifies to the lambdoidal suture, where its filaments ex- 
pand in the skin and occipitalis muscle, and anastomose with those of 
the facial and small occipital nerve. 

The anterior branch is smaller than the preceding ; it goes forward 
and outward under the obliquus capitis superior muscle, and soon di- 
vides into two anastomotic branches, a superior, ascending (JV. anaslo- 
moticus adscendens), and an inferior, descending (JV. anastomolicus 
descendens), which unite, the first with the anterior branch of the first 
cervical nerve, to form the first cervical nervous plexus ; the other with 
the anterior branch of the third, to form the second cervical nervous 
plexus. 

From the upper branch arise filaments which enter the superior cer- 
vical ganglion of the great sympathetic, the sublingual, and the 
pneumo-gastric nerve : one arises even from the bifurcation and goes 
into the superior cervical ganglion ; finally the inferior branch produces 
one which is larger, which descends from behind forward and anasto- 
moses with a similar twig from the anterior branch of the third cervical 
nerve, and with the descending branch of the sublingual nerve. 

(1) Vicq-d'Azyr, loc. cit. 



34 11ESCMPTIVE ANATOMT. 



V. FIRST CERVICAL NERVE. 

§ 1848. The first cervical nerve, called also the suboccipital or the 
tenth encephalic nerve (JV. cervicalis primus, s. supremus, s. occipitalis, 
s. infra-occipitalis, s. decimus cerebri),{\) is frequently the smallest of 
all the spinal nerves, since it is not unfrequently smaller than the last 
sacral nerve ; at least it is always smaller than the other nerves of the 
spinal marrow, except the last. By its situation, origin, and direction, 
it makes the transition from the spinal to the encephalic nerves, for it 
frequently in the same and still more so in different subjects resembles 
the former in some characters, the latter in others. 

Hence for a long time, that is, since Willis lived, it has been consi- 
dered as an encephalic nerve, the tenth cerebral nerve. It is not till 
lately that it has been generally admitted among the spinal nerves, to 
which it is more similar than to the cerebral nerves. 

It arises out of the skull from the upper extremity of the spinal 
marrow between the occipital portion of the basilar bone and the first 
cervical vertebra. 

Very often, perhaps even most generally, although Huber considers 
the existence of two roots as a constant fact,(2) it arises by one an- 
terior root which, like that of the sublingual nerve, comes from the an- 
terior cord of the spinal marrow.(3) 

Even when a posterior root exists, the anterior is much larger than 
it, and is composed of from two or three to seven fasciculi, rarely of 
eight, more commonly of two or three. These fasciculi, situated one 
above another, are also formed of smaller filaments. The posterior root 
presents only from one to three, and rarely four filaments which are 
much smaller, the inferior of which, a remarkable fact, is generally 
much larger than the others : these filaments commonly unite in two 
fasciculi which proceed the superior outward, the inferior upward. 

Even when the posterior root exists, the nerve however is most 
generally formed anteriorly by but one root, the anterior, for the latter 
ascends more than the posterior. 

The posterior root is generally situated behind the accessory nerve ; 
sometimes, however, but very rarely (we have never observed it), it 
passes before. It is then in this latter case unusually near the ante- 
rior, although the ligamentum denticulatum even then always sepa- 
rates it from them. Farther it is constantly nearer the anterior face 
than are the posterior roots of the other spinal nerves. 

(1) G. T. Asch, De primo pare nervorum medullce spinalis, GoUinjren 1750 — Sa- 
batier, Sur les nerfs de la dixieme paire ; in the Mim. presented, vol vit n «3 

(2) De medidla spinali, Gottingren, 1741, § 12. ' ' P ' 

•<3) Morgag-ni (Ep. anat., vol. xvi. 8vo.) also says : Septies ab eo temvore ex mm 
semel anteriores tantamrepen, postcrwres Mas Jibras quaesivi Bis duhiul h W 
Quater procul omni dubio nullas omnino fuisse deprehendi.' Semel aderf- 
sed ne in eo quidem ipso.... ullam prorsus Hbram e sinistris — See nlor. v;„ j, » "" 
Mint, de Paris, 1781, p. 596,-Gordon, p. 214.-Cloquet, p. 631 icq-d'Azyr, 



OF THE NERVOUS SYSTEM. 35 

The posterior root most generally anastomoses with the accessory 
nerve. This is sometimes, although more rarely, the case with the 
anterior. Sometimes the posterior does not unite with the anterior ; it 
goes only to the accessory nerve, in which case the latter after forming 
a small ganglion which however does not constantly exist, sends one 
or two filaments to the anterior root of the second cervical nerve. 

Sometimes instead of the posterior root we find only a plexus which 
anastomoses with the accessory nerve, the filaments of which go 
towards the opening destined for the passage of the first cervical 
nerve.(l). 

When the posterior root and the accessory nerve do not anastomose, 
we generally find a filament which extends from this root to the pos- 
terior root of the second cervical nerve ; but this filament is not con- 
stant. 

The direction of the first cervical nerve is most generally transverse 
from its origin to its emerging from the spinal canal. It not unfre- 
quently proceeds in a direction opposite to that of the other cervical 
nerves, that is, it proceeds a little more from below upward and from 
within outward like the cerebral nerves. 

The superior filaments of the posterior root rarely go upward, and 
the inferior downward. Still more rarely the inferior filaments of the 
two roots have a direction from above downward, while on the con- 
trary the superior commonly follow this direction. 

It is easy to observe that the smallness, the frequent absence and 
the anterior situation of the posterior root, its separation from the an- 
terior, the anastomosis of the latter with the accessory or the second 
cervical nerve, and the direction of the whole nerve, establish a great 
analogy between the latter and the cerebral nerves, while the frequent 
existence also of the roots and their place of origin, establish a 
resemblance with the spinal nerves. 

§ 1849. The trunk of the first cervical nerve passes between the 
occipital portion of the basilar bone and the transverse process of the 
atlas, in the lateral groove of the vertebra below the vertebral artery, 
after forming a very elongated, more or less apparent, and often almost 
imperceptible ganglion. It divides, as usual, opposite the posterior 
edge of the atlas into an anterior and a posterior branch. 

The posterior is larger, and proceeds obliquely backward and up- 
ward, and divides into seven or eight radiating filaments which go to 
the obliquus capitis minor, the obliquus capitis major, the rectus 
capitis major and minor, and the complexus muscles. Some pene- 
trate within the mastoid process. 

The anterior is smaller, goes first from behind forward along the 
vertebral artery to the place where this vessel leaves the vertebral 
canal, it then immediately ascends between the transverse process of 

(1) Vieq-d'Azyr, loc. cit. t p. 296. 



36 DESCRIPTIVE ANATOMY. 

the atlas and the mastoid process. It then divides into four or five 
branches. 

The first turns around on the transverse process of the atlas, pro- 
ceeding from above downward, and anastomoses with one or two as- 
cending filaments of the anterior branch of the second pair. It gives 
off some filaments which unite with the pneumo-gastric, the hypo- 
glossal, and the great sympathetic nerve. 

The second goes to the temporalis muscle. 

The third enters the vertebral canal, is distributed to the vertebral 
artery, and sends filaments to the second cervical nerve. 

The fourth and fifth arise before the transverse process of the first 
cervical vertebra, and are distributed in the rectus capitis major and 
minor muscles. 

The peculiarity in the distribution of this nerve, is, that being situ- 
ated very deeply, it sends off filaments only to these muscles and these 
vessels, and does not extend to the skin. 



CHAPTER II. 

ENCEPHALIC NERVES. 

§ 1850. The following are usually mentioned as general characters 
of the encephalic nerves(l) to distinguish them from the spinal nerves. 

1st. They arise by a single root. 

2d. On leaving the dura-mater they do not produce any special 
ganglion without the concurrence of another nerve. 

3d. They pass through foramina in the bones of the skull, or through 
very irregular fissures formed in them. 

4th. They expand in parts other than the muscles of the skin, par- 
ticularly in the organs of sense and the viscera. (2) 

But of all these characters only the first is with difficulty of general 
application. The fifth pair is an exception to the second, as its semi- 
lunar ganglion is formed without the concurrence of any other nerve : 
we can even to a certain extent mention the olfactory nerve in this 
respect. The glosso-pharyngeal and the pneumo-gastric with the ac- 
cessory nerve, also produce a considerable ganglion shortly after 
leaving the cranium. In fact, these latter unite to give rise to the 
ganglion : but first, the anomaly resulting from it disappears, when it 
is considered that these three nerves should be regarded as forming but 
one; second, almost all the cervical nerves anastomose with each 

(1) J. D. Santorini, Obs. anat., cap. iii.— A. Bergen, De rtervis quibusdam cranii 
ad novem paria hactenus non retails, Erfort, 1738.— Morgagni, Ep. anat xvi — 
Scemmerring, De basi enccphali et originibus nervorum e cranio egredicntium, 
Gottingen, 1778.— Id., Tabula baseos enccphali, Francfort, 1799.— Stieck Dc ouin- 
que prioriJbus cncephali vcrvis, Gottingen, 1791. ' H 

{2) Huber, De medulla spinali Gottingen, 1741, p. 8, 9,-Asch, Dc primo part 
medullas spinalis, Gottingen, 1750, §xxvn. ' '' 



OF THE NERVOUS SYSTEM. 37 

other within the dura-mater by intermediate filaments, before that 
each produces its ganglion. As to the third character, it- does not 
depend on the nerves, but only on the difference in the size and con- 
nections of the bones of the skull and the vertebrae. Besides, it is not 
so exclusive as has been asserted, since we not only sometimes find 
an opening in the first cervical vertebra for the first cervical nerve, but 
also the sacral nerves constantly pass through the foramina of a bone 
originally composed of several pieces iunnoveably articulated to- 
gether. In animals we find foramina for the passage of the corres- 
ponding cervical nerves, not only in the first cervical vertebra, in all 
the mammalia except some apes, but also in the second, but even in 
several of the following in some of these animals, particularly the 
hog. 

The insufficiency of the latter character seems no less evident when 
we consider, first, that the spinal nerves necessarily cannot go to 
parts which are not yet formed : second, that the lumbar and sacral 
nerves are distributed to the genital and urinary organs, and also to 
the latter portion of the intestinal canal. 

It follows then that the distinction between the spinal and the ence- 
phalic nerves is not so well marked as we should be tempted to think 
at first view, and from the assertions of anatomists. Far from it : we 
shall demonstrate that it is very easy to refer the second to the first, 
and to show that they are both constructed after the same type. 

§ 1851. We have already mentioned the principal differences in 
authors in respect to the number of the encephalic pairs they establish, 
and demonstrated that they depend on the different manner of bounding 
the different portions of the centre of the nervous system. But there 
are others depending on the fact, that some cerebral nerves have been 
regarded sometimes as distinct pairs, sometimes only as portions of 
pairs. 

The old anatomists followed the first course, while the moderns, 
adopting the second, have increased the number of cerebral pairs, 
which has gradually risen from seven to twelve, and even according 
to Malacarne,(l) to fifteen. (2) 

The twelve cerebral nerves most generally admitted now, are, pro- 
ceeding from behind forward, 1st, the sublingual ; 2d, the accessory ; 
3d, the pneumo-gastric ; 4th, the glosso-pharyngwal ; 5th, the facial; 
6th, the auditory ; 7th, the external or posterior motor ; 8th, the trifa- 
cial: 9th, the internal or superior motor ; 10th, the common motor; 
11th, the optic; 12th, the olfactory nerve. 

The reasons for admitting a smaller number of nerves are, first, the 
olfactory nerve was long considered, till the time of Massa, not as a 
nerve, but as a portion of the cerebrum : second, till the time of Achil- 
lini, the common external motor nerve of the eye was considered 
as part of the fifth : third, the auditory and the facial nerves have been 

(1) Neuroencephalotamia, Pavia, 1791. 

(2) Malacarne numbers, properly speakinjr, seventeen ; but the seventeenth is the 
posterior root of the suboccipital nerve, and the eleventh the sympathetic nerve. 

Vol. III. 



38 DESCRIPTIVE ANATOMY. 

considered as one till the time of Scemmerring; fourth and fifth, 
till the time of Andersch, the glosso-pharyngceal and the accessory 
nerves have been considered only as portions of the pneumo-gastric 
nerve. Certain anatomists, however, and even before the preceding 
division was established by Scemmerring's publication, had considered 
a greater or less number of the nerves mentioned, as distinct pairs. 

Malacame states the number of the encephalic nerves to be fifteen : 
first and second, by admitting an accessory nerve to the common motor 
and to the superior motor nerve ; third and fourth, by considering the 
three branches of the trifacial as so many distinct nerves, which would 
make sixteen pairs, if instead of distinguishing the glosso-pharyngceal, 
it had not been united to the pneumo-gastric nerve. But this method 
is very objectionable, for even when Malacame had cause to admit his 
accessory nerves to the motors, he could regard them only as the roots 
of these latter, to the trunks of which they unite : second, the three 
branches of the trifacial nerve arise by a common nervous trunk : third, 
the glosso-pharyngceal nerve deserves to be separated from the adja- 
cent nerves, and considered as a distinct pair more than any which 
Malacame insulates. 

Farther, we shall have occasion hereafter to show that it would be 
more convenient to diminish than to increase the number of cerebral 
nerves, but at present we shall follow the common division. 

The principle of the nomenclature of the nerves is not the same in 
all. Formerly the respective situation of their origin was taken for 
them, and they were numbered from before backward. Still later 
this method was preserved, but names drawn from their distribu- 
tion and their uses were applied. This latter mode is undoubtedly the 
best, and we follow it much more willingly, because the first does not 
entirely agree with our mode of considering the nerves, commencing 
at the spinal marrow. 

§ 1852. The cerebral nerves of man differ considerably in respect to 
volume, form, and origin. 

1st. Volume. The cerebral nerves generally diminish in size in the 
following order : the trifacial, the optic, the olfactory, the auditory, the 
common motor, the pneumo-gastric, the glosso-pharyngceal, the facial, 
the external motor, the accessory, the hypoglossal, and the superior 
motor. 

Foiin. Here we may consider, 

1st. The shape. Most of these nerves are round ; the external motor 
however is slightly flattened, and the olfactory is triangular. 

2d. Texture. Almost all are fibrous from their origin ; in the olfactory 
nerve alone there are no distinct fibres. In some, the fibres continue 
separate longer than in others, and they are the more so, the more pos- 
terior the origin of the nerves. They generally unite in fasciculi of 
various sizes before they blend in one trunk. These fasciculi are more 
numarous, and are more similar in size the more posteriorly the nerves 
are situated. The two anterior nerves form only one trunk on leaving 
the cerebrum. ' ° 



OF THE NERVOUS SYSTEM. 39 

We must mention here the differences in their substance and solidity. 
The eleven posterior cerebral nerves are composed, like the spinal 
nerves, of white substance ; the olfactory, on the contrary, contains 
some which is gray. This nerve and the auditory are much softer 
than the others. 

3d. Origin. In this respect, 

a. The cerebral nerves succeed each other from behind forward. 

b. All arise from the inferior part of the cerebrum. Some, particu- 
larly the hypoglossal, the accessory, the pneumo-gastric, the glosso- 
pharyngeal, the posterior motor, the trifacial, the common motor, and 
the olfactory, come from its lower face. The others arise more or less 
from its upper face. 

c. The origins of some, as the trifacial and the common motor, are 
deeply concealed in the substance of the parts of the cerebrum from 
the surface of which they emerge. On the contrary, most of the others 
cannot be traced beyond the surface. 

4th. Direction and progress. All go forward ; but they differ from 
each other in this respect, that the direction of the posterior ten is for- 
ward and outward, while the optic nerve proceeds forward and inward 
at its posterior part, unites with that of the opposite side, and does not 
go outward till after this union. The course of the olfactory nerve 
is obliquely inward and forward. 

I. HYPOGLOSSAL NERVE. 

§ 1853. The hypoglossal nerve, hyoglossien, Ch. the ninth cerebral 
pair, the twelfth of the usual method (N. lingualis medius, Haller ; 
gustatorius, Winslow ; lingualis, Vicq-dAzyr ; hijpoglossus, Wins- 
low),^) arises from the anterior face of the medulla oblongata, passes 
through the anterior condyloid foramen, and is distributed principally 
to the muscles of the tongue. 

It commences by several fasciculi placed after each other from above 
downward. These fasciculi, arranged in a single series about half an 
inch long, describe a curved line, which is convex outward, as the 
superior and inferior are placed a little farther outward than the central. 
They come from the groove between the pyramid and the olivary 
body. The inferior arise below this latter eminence; the superior 
begin a little above the centre of the groove. All are situated a little 
farther outward than the anterior roots of the first cervical nerve, the 
lowest of which are about two lines distant from above downward. 

The whole series of these fasciculi corresponds with much exact- 
ness to the origin of the glossopharyngeal, and the pneumogastric 
nerves, and to that portion of the accessory nerve which arises from the 
medulla oblongata. 

(1) J. F. G. Bcehmcr, Dc nono pare nervorum cerebri, Gottingcn, 1777.— H. F. 
Kilian, Untersuckung uber dusneuute Hirnncrvenpaar y Perth, 1822. 



40 DESCRIPTIVE ANATOMY. 

Thev are always very distinctly separated from each other at their 
origin, "and commence by several radicles, which are themselves gene- 
rally composed of other smaller radicles. 

They vary in their number and situation. We admit from four to 
eight of them. They usually succeed each other uninterruptedly, so 
that the smallest radicles of the different fasciculi touch each other. 
Sometimes, however, we observe some which are more remote from 
the others, and even about a line distant from them, so that this ar- 
rangement, divides them into two or three bundles of different sizes. 

These fasciculi reunite in cords which are generally two and some- 
times three in number, each of which passing through a special open- 
ing in the dura-mater, proceeds from behind forward, from below up- 
ward, and from within outward, towards the posterior orifice of the 
anterior condyloid foramen. They rarely unite in a single trunk 
before they enter the dura-mater. Sometimes even an osseous septum 
divides them for the whole extent of the condyloid canal, into at least 
two halves, which unite only at the external orifice of this canal. 

On leaving the cranium the trunk goes downward, proceeding on 
the upper part of the condyle, and covered outward in the extent of 
about an inch, by that of the pneumo-gastric nerve, with which it is 
generally united by filaments, it passes on the internal carotid artery, 
and descends from behind forward between the laryngceal branch of 
the pneumo-gastric and the accessory nerve. 

In this place it unites at first near the summit of the transverse 
process of the first cervical vertebra forward and upward by a con- 
siderable filament, with the pneumo-gastric nerve downward and 
backward, with the first cervical nerve and the great sympathetic 
nerve bj' another filament which ascends from the anterior branch of 
the first, and from the superior cervical ganglion, before which it is 
situated. It then descends, covered outward by the pneumo-gastric 
nerve, the posterior belly of the digastricus muscle, the stylo-glossus 
muscle, and the internal jugular vein, inward by the internal carotid 
artery, and gives ramifications to the submaxillary gland. When as 
high as the third cervical vertebra, it passes before the external carotid 
artery, and forming a large arch, which is convex downward, it. goes 
from behind forward and from below upward, towards the genio-glossus 
muscle, along the inside of the posterior and inferior hyoid bone. 

At the origin of its arch it gives off a considerable and very con- 
stant branch, the descending cervical nerve (R. descendens noni), 
which goes downward and forward, first along the anterior face of the 
external carotid artery, where it is intimately united to the trunk of 
the pneumo-gastric nerve by cellular tissue, then to the inner side of 
the internal jugular vein, passes above the superior thyroid artery, 
goes still farther forward on leaving this point, gives off forward and 
inward a branch which terminates in the anterior belly of the omo- 
hyoideus muscle, sends others to the muscles of the larynx, and again 
uniting in the middle of the neck with the descending nerve which 
comes from the anterior branches of the second and third cervical 



OF THE NERVOUS SYSTEM. 41 

nerves, thus forms an arch, the convexity of which is well marked and 
turned forward. 

The convexity of this arch usually gives rise to two branches, which 
descend along the anterior side of the internal jugular vein. The 
superior is smaller, and retrogrades to go to the anterior belly of the 
omo-hyoideus muscle. The inferior is larger, passes under the anterior 
belly of this muscle, goes downward and forward to the external face 
of the sterno-thyroideus muscle, distributes several filaments in this 
muscle and the sterno-hyoideus muscle, and anastomoses in this place 
by a small but constant filament, with the diaphragmatic nerve. Some 
ramifications of this branch enter the chest, particularly on the left 
side, and extend to the upper part of the pericardium. 

The trunk of the hypoglossal nerve immediately gives ofT some 
branches which go downward into the thyro-hyoideus muscle. Thence 
it rises again, first below the tendon of the digastricus muscle, then on 
the external face of the hyoglossus muscle, gives filaments, of which 
the upper anastomose frequently from its upper and lower parts, but 
principally from this latter to the muscles of the larynx, then to the 
hyoglossus, to the genio-hyoideus, and to the genio-glossus muscle, 
unites with the lingual nerve of the third branch of the trifacial in the 
upper and anterior part of the hyoglossus muscle, by two or three con- 
siderable filaments, and afterwards extends almost to the point of the 
tongue by ramifications which proceed between the fibres of the hyo- 
glossus muscle. 

At the body of the hyoid bone the trunk of the nerve turns on the 
Ungual artery, and enters the genio-glossus muscle, in which it ter- 
minates by branches, some of which go to the lower face of the point 
of the tongue. 

We cannot follow the filaments of the hypoglossal nerve into the 
integuments of the tongue ; they stop in the muscles of this organ. 
From this circumstance we might deduce the very probable conclusion 
that it serves only to excite the motions of the muscles, and that it is 
not the proper gustatory nerve, although it communicates by very 
large anastomoses with the lingual branch of the trifacial nerve, the 
ramifications of which penetrate distinctly into the integuments of the 
tongue, Another circumstance gives more weight to this conjecture, 
viz. the analogy between it and the motory nerves of the other organs 
of the senses which receive both nerves of sensation and of motion. 
That these two orders of nerves fulfill different functions, is demon- 
strated by the observation, that alterations, the primitive or accidental 
destruction of one of them, is attended only with the loss of one of the 
two faculties of the tongue, that of the taste when the affection is 
situated in the lingual branch of the trifacial nerve, and that of motility 
when the hypoglossal nerve is afFected.(l) The loss of taste in one 

(1) The sense of taste is lost in trisma, but the levator muscles of the lower jaw 
receive their nerves from the fifth pair and not from the hypoglossal nerve (Haller, 
El phys vol v. p. 112). The congenital absence of taste has been observed in a 
patient where the lingual branch went to the occiput and not to the tongue (Colombo, 
here anat., Paris, 1762, p. 486 ) 



42 DESCRIPTIVE ANATOMY. 

case where the hypoglossal nerve was injured(l) even when this 
lesion would not have been admitted as probable, would not prove 
that the two nerves concurred in the function of taste, for on one side 
the lesion might produce this effect only from the connections between 
the two nerves ; and secondly a case cited by Heuermann would 
farther prove that it cannot be admitted, since on account of the distri- 
bution of the hypoglossal nerve and of the lingual branch of the 
trifacial nerve, the hypoglossal nerve could not alone be the nerve of 
taste, as should be concluded from this fact, considered as a peremp- 
tory argument in favor of the power attributed by the author to the 
nervous trunk supposed to be injured. 

But the difference of function between the two nerves is not proved 
by the cases where the loss of the motion of the tongue without that 
of taste, or the loss of taste without that of the motion of the tongue(2) 
in general, have been observed, since the same phenomenon is seen 
in other parts which receive only one nerve, and which cannot conse- 
quently be explained in the same manner. 

II. ACCESSORY NERVE. 

§ 1854. The accessory nerve,(3) trachelo dorsal, Ch. (JV*. spinalis 
ad par vagum accessorius, accessorius Willisii),(4) arises by numerous 
filaments from the posterior part of the lateral face of the posterior cord 
of the spinal marrow, ascends between the posterior roots of the upper 
six cervical nerves and the ligamentum denticulatum, nearer the for- 
mer than the latter, consequently also nearer the posterior than the 
anterior roots of the cervical nerves, penetrates into the skull through 
the occipital foramen behind the vertebral artery, receives some fila- 
ments from the latter parts of the medulla oblongata, is situated below 
near the pneumo-gastric nerve, with which it emerges from the skull 
through the posterior foramen lacerum, and is distributed partly in 
the upper region of the pharynx, partly also in some muscles of the 
back. 

Its lowest and smallest root usually arises at the height of the supe- 
rior filament of the posterior roots of the seventh cervical pair ; the 
second at that of the upper part of the posterior root of the fifth ; the 
third and fourth at that of the upper part of the fourth ; the fifth oppo- 
site that of the third ; the sixth between the second and third ; and the 
seventh opposite the posterior root of the second. Many of these roots 

(1) Heuermann, Physiologie, vol. ii. p. 295. 

(2) Scemmerring, Nervenlehrc, p. 262.— Scarpa, Tab. ncurol , Pavia 1794 d. 
16-17. Two cases. ' ' r 

(3) Often termed the accessory nerve of Willis, but wrongly, as it had previously 
been figured by Eustachius and described by Coiter. 

(4) J. F. Lobslein, De nervo spinali ad par vagum accessorio, Strasbunr 1760 — 
A. Scarpa, Uber den zum achtcn Paare dcr Gehirnnerven hinlaufcnden Beinerren 
des Ritckenmarnes ; in the Abhandl. dcr Josephsakad, vol. i. p. 385.— Its ori<nn has 
been described perfectly by Huber, De medulla spinali, speciatim dc ncrvS ab ea, 
provenicntibus, Gottingen, 1741, § vii-xi. 



OF THE NERVOUS SYSTEM. 43 

sometimes communicate in one or several points with the anastomotic 
filaments of the middle and superior cervical pairs. 

Usually no root of the accessory nerve arises from a higher point of 
the spinal marrow. 

Sometimes, however, the whole posterior root of the first cervical 
nerve joins it and forms with it a small ganglion. But this ganglion 
is not constant when the nerves unite, and we should even think it 
extremely rare, since it has never been observed by Haller, Ash, 
Lobstein, and Scarpa, who have remarked only a slight thickening of 
the nerve.(l) We have never seen it but a few times, notwithstanding 
our numerous researches. 

Three or four roots generally arise within the skull from the lateral 
face of the posterior cord of the medulla oblongata ; these are behind 
the roots of the hypoglossal nerve. 

These ten or eleven roots gradually become longer and thicker 
from below upward, and go towards the trunk of the nerve at angles 
which are more acute the lower their origins. The lowest is in great 
part concealed in the pia-mater, through which it only penetrates. 
The spinal roots also are usually single, while those arising from the 
medulla oblongata are generally composed of two short radicles united 
at an acute angle, each of which is formed by three or four filaments. 
These radicles, one of which is superior, the other inferior, and the se- 
cond of which ascends in a more perpendicular direction, soon reunite. 
In considering the whole series of roots, we recognize that they gra- 
dually become more anterior from below upward. 

The nerve enlarges as it ascends, goes imperceptibly outward, and 
is attached above by short filaments to the trunk of the pneumo-gastric 
nerve. 

The accessory nerve never arises lower than the point indicated. 
On the contrary it often commences higher, opposite the sixth cervical 
vertebra, sometimes even but more rarely opposite the fifth. In some 
subjects it receives from the spinal marrow only two or three roots, 
which are then proportionally thicker. 

The number of the filaments from the medulla oblongata is some- 
times less than we have mentioned : it is rarely and perhaps never 
greater. Sometimes they resemble by being single those which arise 
from the spinal marrow. 

So likewise the accessory nerve does not always arise exactly in the 
same place. 

It is very rarely united by a filament with the posterior root of the 
second cervical nerve. (2) 

It does not anastomose with the hypoglossal nerve within the 
skull. (3) 

(1) Scarpa, loc. cit., p. 396. 

(2) Scarpa, loc. cit., p. 395. This anatomist has observed this union only twice in 
his numerous dissections We have found it only once. 

(3) Scarpa, loc. cit., p. 397, does not admit this assertion of Winslow. We have 
never seen the anastomosis mentioned by this latter. 



44 DESCRIPTIVE ANATOMY. 

It generally passes through the dura-mater in connection with the 
pneumo-gastric nerve : but sometimes also it emerges through a spe- 
cial opening behind the latter, with which however it reunites. 

All these differences are observed not only in different persons, but 
frequently in the same person on different sides of the body. 

In passing through the dura-mater the accessory nerve is inclosed in 
a sheath with the pneumo-gastric nerve ; but before emerging through 
the posterior foramen lacerum it divides into an internal and an ex- 
ternal branch. 

The internal branch gives off first two branches which unite with 
each other and with a third which descends from the pneumo-gastric 
nerve, and produces the superior pharijngozal nerve. It then receives 
some filaments from the pneumo-gastric nerve, sometimes communi- 
cates with the hypoglossal nerve, then reunites with the trunk of the 
pneumo-gastric nerve to form a ganglion. 

The external branch proceeds for about two inches descending 
deeply behind the internal jugular vein, at first between this vessel and 
the occipital artery, then between it and the stemo-cleido-mastoideus 
muscle. It turns a little on this muscle and goes forward, sometimes 
passes through it, gives to it filaments which anastomose with those 
of the third cervical nerve, then continues to descend but from before 
backward, passing on the internal jugular vein, enlarges considerably 
by uniting with two anastomosing branches, the upper of which arises 
from the anterior branch of the second cervical nerve and the lower 
from that of the third, passes on the levator anguli scapula; muscle, 
anastomoses with the ramifications of the fourth and fifth cervical 
nerves, and comes to the internal face of the trapezius, in which it is 
distributed. No other muscles receive filaments from it. 

III. PNEUMO-GASTRIC NERVE. 

§ 1855. The pneumo-gastric, the par vagum, the middle sympa- 
thetic, the pulmonary, the vocal nerve, the eighth, or according to the 
new calculation, the tenth pair ( JV*. pneumogastricus, Chaussier ; N. 
vagus, N. sympathicus medius, Winslow ; N. pulmonalis, Bartels;(l) 
par octavum, Willis ;(2) decimum, Andersch),(3) arises from the 
side of the posterior prolongation of the cerebellum between the acces- 
sory and the glosso-pharyngceal nerves, emerges from the skull 
through the posterior foramen lacerum, and descending is distributed 

(1) Respiration, p. 210. 

h) This term, however, includes the following- or the g-losso-pharyng-eal nerve 
(3) Neubauer, Descript. ncrv. cardiac— Andersch, in the JSov. coram Gott vol ii. 
published in Haase, Cerebri nervorumquc anat., Leipsic, 1781, and in Ludwie 
Script, neurol. mm. vol. n.— Walter, De nerv. abdom., Berlin, 1800.— Wrisbcrir De 
ganglio plexuque semilunar!, &c. sect, ii., De pari octavo; in the anmo r„™™.r,i 
vol. i. 1800—Scarpa, Tab. neurolog, Pavia, 1794. a '" C CummenL 



OF THE NERVOUS SYSTEM. 45 

in the upper part of the alimentary canal, the stomach ; second in the 
organs of respiration ; hence the term pneumo- gastric. 

§ 1856. It arises by from ten to sixteen filaments from the lower 
part of the lateral face of the posterior prolongations of the cerebellum. 
The inferior are situated far behind the anterior, and form a series 
which is general^ single and five or six lines long. Sometimes, how- 
ever, several are more anterior than the others ;(1) this is particularly 
the case with those at the top of the series, although there is no dis- 
position indicating any tendency to produce distinct roots. On the 
contrary, in this formation the pneumo-gastric nerve is similar to 
the formation of the anterior cerebral nerves, as its origin is thus more 
rounded, which form is remarkable in several of the mammalia, parti- 
cularly the ruminantia. These filaments arise principally towards the 
anterior and inferior edge of the posterior prolongation of the cerebel- 
lum, in the groove between this prolongation and the olivary body. 
They do not extend so high as this latter, and terminate below long 
before those of the hypoglossal nerve. Some of them frequently anas- 
tomose with the transverse medullary stria? on the floor of the calamus 
scriptorius, and hence these striee seem to concur in their formation. (3) 
Others, particularly some of the inferior, come from the lower extremity 
of the olivary body. (4) 

These filaments are generally single, and not cleft at their internal 
part. They are sometimes separated and sometimes united from their 
origin in three or four fasciculi. The inferior are commonly very inti- 
mately connected with the accessory nerve. The superior most gene- 
rally communicate by a transverse filament with the glosso-pharyngceal 
nerve even within the skull. 

These filaments and fasciculi unite in a flattened trunk about one 
line and a half broad, one quarter or one fifth of a line thick, and al- 
ways larger at its upper part where they are interlaced with each 
other. This trunk goes outward and backward. It is inclosed in a 
small canal of the dura-mater, through which it comes from the cranium, 
through the anterior part of the foramen lacerum, before the origin of 
the internal jugular vein. It is separated from this vein by a promi- 
nence of bone which comes from the petrous portion of the temporal 
bone or from the occipital bone, or from both, and from the accessory 
and the glosso-pharyngoeal nerves by the dura-mater. 

The fasciculi hitherto distinct do not entirely unite in a rounded 
cord except wiihin this canal. The rounded cord on leaving the fora- 
men lacerum is united very intimately by mucous tissue with the 

(1) Coopmans, Neurol., p. 118. — Scemmerring-, p. 102. 

(2) Santorini, Scplcmdccim tabula, p. 27. — Girardi, ibid. — Vicq-d'Azyr, in the 
Mem. dc Paris, 1784, p. 594. 

(3) Desmoulins, Sur Ic rapport qui unit le dcvcloppcment du ncrf pneumo-gas- 
triquc d criui des paroia du qualricmc vcnlriculc ; in the Journ. dephys. experimen- 
tale, vol. iii., p. 362. 

(4) Vicq-d'Azyr, loc. cil., p. 594. 

Vol. III. 7 



46 DESCfUPTIVE ANATiOli 

glosso-pharyngceal nerve, the hypoglossal and the ascending branch of 
the superior cervical ganglion. It is situated at first behind the glosso- 
pharyngceal and before the hypoglossal nerve, but it soon passes be- 
hind this latter, is separated from the glosso-pharyngceal nerve by the 
internal jugular vein, leaves the hypoglossal nerve on the transverse 
process of the first cervical vertebra, and descends outward and a little 
backward before the primitive carotid artery, between it and the in- 
ternal jugular vein, intimately united to these two vessels by a mucous 
tissue destitute of fat and more loosely connected to the intermediate 
filaments of the sympathetic nerve which are situated behind it and 
placed in the rectus capitis major anticus and the longus colli mus- 
cles.(l) 

In passing through the foramen lacerum the pneumo-gastric nerve 
anastomoses by some filaments with the accessory nerve, and shortly 
after leaving this opening it communicates also with the glosso-pharyn- 
gceal nerve and the superior cervical ganglion. It then gives off a 
branch which unites with two filaments from the inner branch of the 
accessory nerve, and gives rise to the pharyngeal or superior pharyn- 
geal nerve (JV*. pharyngeus, s. pharyngeus superior, s. primus.) 

This nerve goes obliquely from above downward and from without 
inward on the inside of the internal carotid artery, sends an anasto- 
mosing filament to the glosso-pharyngceal nerve, bulges a little, and 
forms at the height of the middle constrictor of the pharynx a consi- 
derable plexus termed the pharyngeal (plexus pharyngeus). This 
plexus receives filaments from the laryngceal, the glosso-pharyngceal 
nerves, and from the superior cervical ganglion ; its filaments are dis- 
tributed principally in the middle constrictor, but some go to the upper 
constrictor of the pharynx : a few descend along the primitive carotid 
artery, where they anastomose with the ramifications of the glosso- 
pharyngceal and the superficial cardiac nerves. 

The inferior pharyngeal nerve ( JV. pharyngeus inferior, s. minor), 
which also is not constant, arises directly below the superior pharjn- 
gceal nerve. This nerve soon anastomoses with the preceding, and 
also with one or several of the anterior filaments of the superior cer- 
vical ganglion, sends filaments to the pharyngceal plexus, and is dis- 
tributed in the middle constrictor of the pharynx. 

At the place where the pharyngceal nerves are given off and some- 
times also a little higher, the trunk of the pneumo-gastric nerve be- 
comes much thicker and its texture is closer for about an inch : its 
fasciculi separate very much, and a reddish gelatinous substance is 
deposited between them. A real ganglionnary plexus then forms. The 
remnant of the internal branch of the accessory nerve after sending an 
anastomotic twig to the pharyngceal nerve enters this plexus at about 
its centre, sometimes in one branch, sometimes also in several filaments 
which ramify and interlace differently, so that this branch forms the 



OF THE NERVOUS SYSTEM. 47 

lower part of the plexus, and seems also to belong to the pneumo-gas- 
tric nerve. 

The trunk of the pneumo-gastric nerve is in fact directly attached to 
this ganglion from before backward ; but it is sometimes, although 
rarely, connected with it only by some filaments of communication. 

A more distinct development of this plexiform dilatation of the nerve 
occurs when it divides into two portions which unite only at the lower 
part of the neck ; but such an arrangement is extremely rare : it has 
been observed only once in five hundred cases, and this was on the 
right side.(l) 

The superior laryngceal nerve (JV. laryngozus superior), which is 
commonly larger than the inferior, usually arises from the upper part 
of this ganglion. 

This nerve descends between the internal carotid artery and the su- 
perior cervical ganglion, most generally anastomoses by one or several 
filaments with this latter, the pharyngceal plexus, and the hypoglossal 
nerve, and divides into an external and an internal branch. 

The external goes inward, and sends filaments to the inferior con- 
strictor muscle of the pharynx, the crico-thyroideus, the sterno-thy- 
roideus, and the hyo-thyroideus 'muscles, to the thyroid gland, and to 
the membrane of the pharynx ; these filaments enter the cavity of the 
larynx between the cricoid and thyroid cartilages. 

The internal branch passes through the hyo-thyroid membrane be- 
tween the hyoid bone and the thyroid cartilage. It distributes soft 
and thick filaments in the membrane and glands of the epiglottis, the 
mucous membranes of the pharynx and larynx, several small muscles 
of the larynx, particularly the arytenoideus and the crico-thyroideus, 
and anastomoses with the filaments of the inferior and recurrent laryn- 
gceal nerve. 

After the superior laryngceal nerve, we see arise either from the 
ganglionnary plexus or directly below it some filaments which are not 
constant ; these unite to the descending branch of the hypoglossal 
nerve, and also to the first cervical nerve, and to the soft nerves which 
go to the internal carotid artery. 

After giving off these branches, the trunk of the pneumo-gastric 
nerve becomes more compact, and descends in the manner mentioned 
above, but gives off no ramifications. It then represents a cord com- 
posed of less distinct fasciculi and which is generally uneven by a kind 
of indentation, but its surface is surrounded here and there by very 
minute filaments which interlace like a plexus. (2) It gives off about 
an inch or an inch and a half above the origin of the primitive carotid 
artery (but an inch higher on the right than on the left side), and 
at about the centre of the neck, on both sides, the cardiac nerves (R. 
cardiaci). These descend from within outward and from behind for- 

(1) Wrisberg, De nervis pharyvgis ; in Ludwig, loc. cit., vol. iii., p. 57. 

(2) Prochaska, De struc. ncrv., tab. ii., fisr. 7, 7, cc— Rcil, Dc struct, ncrr., tab. i.. 
flg. 2, 3, 4. 



48 DESCRIPTIVE ANATOMY. 

ward in the carotid artery and the innominata trunk, anastomose with 
the superficial cardiac nerves, and are distributed to the arch of the 
aorta. We generally find three or four on the right side, the upper of 
which is the largest and most constant. There are one or two on the 
left side. 

The trunk of the pneumo-gastric nerve goes forward, is situated 
behind the innominata vein, passing on the right before the subclavian 
artery, on the left before the arch of the aorta, thus comes into the 
chest, enlarges considerably, and divides into two halves, of which the 
lower and larger is the continuation of the trunk, and the upper is 
smaller, and is termed the inferior laryngozal ascending or recurrent 
nerve, tracheal, Ch. (JV. recurrens, s. adscendens, s. laryngeus in- 
ferior). 

The two recurrent nerves arise within the chest, the left much 
lower than that of the right side. They ascend first from before back- 
ward, then vertically, send some filaments to the cardiac nerves which 
come from the pneumo-gastric, the middle and inferior cardiac nerves 
which come from the ganglionnary nerves, form with them a plexus, 
then turn from before backward, the right on the right subclavian 
artery, the left on the extremity of the arch of the aorta, and are 
placed behind the primitive carotid and inferior thyroid artery, between 
the trachea and the esophagus, and rise to the larynx. In this 
course they give off first the branches called the superior tracheal 
nerves (R. tracheales superiores), which descend before the trachea 
and anastomose with the preceding, arrive at the bronchia and the 
pulmonary plexus of their side, are distributed in the membrane of the 
trachea, the pharynx, and the thyroid gland, and communicate with 
some filaments of the cervical portion of the sympathetic nerve. 

Finally, when as high as the larynx the recurrent nerve is distri- 
buted in the inferior constrictor of the pharynx and the cricoarytenoid 
muscles, enters the cavity of the larynx between the cricoid and 
thyroid cartilages, and terminates in the thyroid cartilage, the arytenoid 
muscle, and the mucous membrane of the larynx, by anastomosing 
by several branches with the superior laryngoeal nerve. 

The recurrent nerve is sometimes double, but this is rare, and when 
it occurs it is always on the right side, if we judge from observations 
made hitherto. The unusual nerve is smaller than the other, and 
arises from the trunk some lines below it, turns like it on the sub- 
clavian artery, ascends between the esophagus and the trachea, anas- 
tomoses by a large twig with the normal recurrent nerve, and is dis- 
tributed with the latter.(l) 

This anomaly seems to indicate an effort to establish a perfect simi- 
larity between the right and left sides, since the recurrent nerve 
always arises lower than that of the right side. 

It is very probable that the recurrent nerve results from the plexi- 
form division of the trunk of the pneumo-gastric, and that its existence 

(1) Wrisberg, De nereis abdominis, Gottingcn, 1780. 



OF THE NERVOUS SYSTEM. 49 

is connected with the primitive shortness of the neck, since the larynx 
is much nearer its origin in the early periods of life than subsequently. 
This hypothesis would explain its arrangement in the same manner 
as the high origin and long course of the spermatic vessels. Farther, 
it is impossible to deny the analogy between the distribution of the 
nerves and vessels in this region of the body, since the superior and 
inferior laryngoeal nerves and the superior and inferior thyroid arteries 
manifestly correspond. 

§ 1857. The trunk of the pneumo-gastric nerve having given off 
the recurrent nerve, goes backward on the posterior face of the trachea. 

There it supplies first five or six inferior tracheal nerves (V.tra- 
cheales inferiores), some of which proceed before, others behind the 
trachea. The former anastomose with the filaments of the superior 
tracheal nerves and with others coming from the inferior cervical 
ganglion. Some descend before on the ramifications of the bronchia? 
and of the pulmonary artery. Others enter the muscular and mucous 
tunics of the trachea, bronchia, and esophagus, and terminate in the 
pulmonary plexus (plexus pulmonalis) . 

This plexus commences directly above the bronchia of each side. 
It is formed principally by the fasciculi of the trunk of the pneumo- 
gastric nerve, between which there is a very vascular mucous tissue. 
It extends behind the bronchia? into the substance of the lungs, 
surrounding the finest ramifications of the bronchial tree, to the mus- 
cular tunic, and even to the mucous membrane to which it sends fila- 
ments. Beside the trunk of the pneumo-gastric nerve which develops 
itself to give rise to it, it also receives some filaments which are less 
numerous, from the superior thoracic and from the inferior cervical 
ganglion of the great sympathetic nerve. 

Five or six fasciculi on the right side and only two or three on the 
left, arise from the lower part of each of these two pulmonary plexuses. 
These fasciculi are first situated very far from each other, but fre- 
quently anastomose by intermediate filaments. After passing some 
lines they unite on each side in a cord, which is the continuation of 
the trunk of the pneumo-gastric nerve, and the right of which is larger 
than the left. These cords descend, that of the left before, that of the 
right behind, and at the side of the esophagus. 

In their course they frequently anastomose principally by anterior 
filaments which descend from the right cord, send filaments to the 
esophagus, and others which are smaller to the aorta, and enter the 
abdomen with the esophagus, passing through the esopahgeean fissure 
of the diaphragm. 

The pneumo-gastric nerve terminates in the stomach. That of the 
right side which is the largest, goes to the right portion and the pos- 
terior face of the viscus ; that of the left side is distributed in its left 
part and on its anterior face. 

The right forms around the cardiac orifice a large plexus, from 
which numerous filaments arise, some of which are distributed to the 
posterior face of the stomach ; others situated behind the coronary 



50 DESCRIPTIVE ANATOMY. 

artery of the stomach, proceed along its small curve to the pylorus, 
and there anastomose with those of the left nerve and with the superior 
gastric plexus of the great sympathetic nerve : finally, some which do 
not belong to the stomach pass behind it, arrive at the right portion of 
the solar plexus and also the plexuses which come from this latter on 
the right side, and are distributed to the hepatic artery and its branches, 
to the vena-portae, the duodenum, and the pancreas. 

The left divides at the cardiac orifice into several branches which 
separate in rays, communicate less frequently, follow the small curve 
of the stomach from left to right, send ramifications to the anterior face 
of this viscus, anastomose near the pylorus with the filaments of the 
right pneumo-gastric nerve, and leaving the stomach, terminate anteri- 
orly before the pylorus, in the hepatic plexus formed by the ganglion- 
nary nerve. 

IV. Or.OSSO-PHARVNOCF.AE NEKVE. 

§ 1858. The glosso-plianjngozal nerve (JV, glosso-pharyngccus, Hal- 
ler ; s. lingualis pneumogastrici, Vicq-d'Azyr; s. octavus, Andersch), 
has been considered until lately as the anterior part of the pneumo- 
gastric nerve. In fact, if we regard its origin, the communications 
between it and this nerve, both within the skull and at its passage 
through the posterior foramen lacerum, finally the manner in which it 
is distributed, we discover that it really forms a part of the pneumo- 
gastric nerve, but it is so largely developed that it may be considered a 
proper and distinct nerve. It arises by five or six filaments, which 
may be easily separated from each other, and the anterior of which are 
generally smaller than the posterior. It arises between the pneumo- 
gastric and facial nerves, some distance behind the latter, but directly 
before the upper filaments of the first, from which its own cannot be 
separated. It comes from the upper part of the lower face of the 
inferior prolongation of the cerebellum, from the depression between 
this cord, the olivary bodies, and the posterior edge of the annular pro- 
tuberance, directly behind the latter, from which several of its filaments 
sometimes emanate. Tt goes outward and at first a little forward, covered 
by the fourth lobe of the cerebellum, usually anastomoses within the 
skull by a large branch with the pneumo-gastric nerve,(l) and after 
proceeding five or six lines, passes through the arachnoid membrane. 
It is round and about a half or three quarters of a line thick, and 
emerges from the skull through the anterior part of the posterior fora- 
men lacerum, directly before the pneumo-gastric nerve, but inclosed in 
a special canal of the dura-mater. About four or six lines from its 
entrance into this canal, it becomes a small, oblong, rounded, and gene- 
rally very distinct ganglion about five lines long, which extends into 
the, canal of the dura-mater and the anterior part of the foramen 
lacerum. 

(1) Andersch, Frugm. descript. nerv. cardiac, in Ludwig, he. c il.. vol. ii. p. 115. 



OF THE NERVOUS SYSTEM. 51 

This ganglion gives off, above, a filament, which enters into the 
cavity of the tympanum, and then divides into two branches ; one 
ascends along the- promontory, gives off a small filament to the mem- 
brane of the foramen rotundum, and passes through the petrous por- 
tion of the temporal bone to the superficial temporal nerve, and the 
other passes below the osseous portion of the Eustachian tube, and 
goes to the carotid canal, where it anastomoses with the great sym- 
pathetic nerve.(l) 

The ganglion also gives off other filaments, which pass through the 
canal of the dura-mater to go to the trunk of the pneumo-gastric, to 
the accessory, and the great sympathetic nerves. 

After emerging from the posterior foramen lacerum, the glosso- 
pharyngeal nerve is separated from the pneumo-gastric trunk by the 
internal jugular vein, before which it is situated. Thence it goes 
downward and forward, passing on the internal carotid artery, descends 
situated at first closely on the outside, then on the anterior part of this 
artery, between it, the external carotid artery, and the stylo- pharyngceus 
muscle, passes between this muscle and the glosso -pharyngceus muscle, 
then between this latter and the hyoglossus, and thus comes to the 
lower and posterior part of the tongue. 

On leaving the skull it sends a filament of anastomosis to the stylo- 
hyoid branch or to the digastric branch of the facial nerve and another 
to the trunk of the pneumo-gastric nerve. It then gives off one or two 
which descend along the internal and the primitive carotid arteries, 
anastomose first with the pharyngceal branch of the pneumo-gastric 
nerve, and then going to the lower part of the neck communicate with 
some filaments of the sympathetic nerve particularly with the super- 
ficial or even the middle cardiac nerves. Still farther on, it sends off 
three or four filaments to the stylo-pharyngeus muscle, and also to the 
middle and superior constrictors of the pharynx and to the amygdalae, 
and some which enter the pharyngceal plexus of the pneumo-gastric 
and the ganglionnary nerve. 

The glosso-pharyngceal nerve then passes between the styloglossus 
and hyoglossus muscles ; then situated in the tongue below the 
lingual nerve of the fifth pair and above the hypoglossal nerve, both 
larger than it and with which it does not communicate at least by very 
evident filaments, it is distributed partly in the muscles of the tongue, 
the membrane of the soft palate and the amygdalae by several ramifi- 
cations which interlace like a plexus ; partly in the integuments of the 
base of the tongue, its large papillae, and the mucous membrane of the 
epiglottis by other filaments which are situated lower and nearer the 
median line than the preceding, and pass from below upward through 
the substance of the tongue. 

(1) Rosenmullcr, Handbuch dcr Anatomic, 1816. p. 407.— Jacobson, in the Ada rcg. 
societ. Ilafnicnsis mcdicac, vol. v. Copenhagen, 1818. p. 292.— This anastomosis has 
been doubted by Kilian, but is admitted by Lobstein. 



52 DESCRIPTIVE ANATOMY. 



V. AUDITORY NERVE. 



§ 1859. The auditory or acoustic nerve, labijrinthique, Ch., the soft 
portion of the seventh pair ( JV. auditorius, s. acusticus, s. portio mollis 
nervi acustici) } (l) is very soft, but harder than the olfactory and the por- 
tion of the optic nerve behind the decussation ; it generally communicates 
so evidently with all the white striae of the floor of the calamus scrip- 
iorius, or at least with several of them, that it may be said to arise 
partially from it. 

Its upper and external part is formed by these striae. The fibres 
connected with it follow one another from before backward and are 
separated by unequal and inconstant spaces ; they turn on the inferior 
prolongations of the cerebellum, on the surface of which they are inti- 
mately connected. Their direction is forward and downward, the 
anterior proceeding transversely, the posterior obliquely from below 
upward. 

The inner part of the nerve is larger than the external portion, but 
they are not separated ; it arises below and farther forward than it from 
the lateral face of the spinal prolongation of the cerebellum, directly 
before and above the glosso-pharyngceal. nerve and the upper part of 
the pneumo-gastric nerve. 

The trunk of the nerve then goes forward, outward and downward 
on the posterior edge of the transverse prolongation of the cerebellum, 
and is united to its upper face so intimately for about three lines, that it 
may properly be considered as arising from this part of the encephalon. 
It is slightly covered outward by the fourth lobe of the cerebellum, being 
often attached in this place to its medullary substance, so that we may 
admit also that it partially arises there, which is worthy of note but 
not astonishing, on account of the analogy resulting from it with what 
is seen in the other two nerves, the optic and olfactory, which are only 
nerves of sense. 

Its internal face is grooved lengthwise, and receives the facial nerve. 
It is soft at its origin, and we do not perceive there distinct fibres, but 
on leaving the encephalon it evidently becomes fibrous and still more 
solid. 

On leaving its origin the auditory nerve goes obliquely forward, 
outward, and upward, and soon penetrates the internal auditory fora- 
men, which is much larger than it. It then divides into two branches, 
which continue united externally to its base ; the anterior enters the 
cochlea and the posterior, the vestibule and the semicircular canals. 
We shall describe these branches when speaking of the ear. 

(1) J. F. Meckel, Obs. anat. sur la glandc pineale, sur la cloison transparent rt 

surVongine dc la sepheme pairc, in the Mem. de Berlin, 1765. p. 91-100 A 

Scarpa, De nervo auditorio, in his Anat. disquis. de auditu et olfactu Pavia, 1789 
sect. ii. cap. iii. ' ^ ' 



OF THE NERVOUS SYSTEM. 53 



VI. FACIAL NERVE. 

§ 1860. The facial or small sympathetic nerve, the hard portion of 
the seventh nerve, iheseventh pair, theseventh cerebral nerve (N. facialis, 
s. sympathicus minor, s. communis facili, s. portio dura septimi, s. 
nervus primus septimi paris, s. par septimum)(\) is much smaller than 
the auditory nerve ; it arises by two roots which are generally distinct, 
although placed one against the other. One is external and posterior, 
the other much larger is internal and anterior. It arises within, below, 
and before the auditory nerve, which receives it in a groove situated 
along its internal face, directly at the side of this nerve and before the 
glosso-pharyngEeal nerve. It arises from the posterior edge of the 
annular protuberance, from the uppermost part of the lower face of the 
rachidian prolongation of the cerebellum ; sometimes, also, according 
to Malacarne, by several filaments from the floor of the fourth ven- 
tricle, that is, from the most anterior transverse medullary striae. The 
filaments from the annular protuberance, particularly the internal, seem 
to come only from this tubercle ; but examining them attentively, we 
see that they are separated from the principal root only by the pos- 
terior fibres of the protuberance existing between this latter and 
them. (2) Very possibly, however, from this reason they are in fact 
separated from the principal root, and first arise from the pons Varolii. 
The external root of the nerve, which is much smaller than the in- 
ternal, is always formed of three or four filaments which unite anteri- 
orly in one or two fasciculi. It is situated between the internal root and 
the auditory nerve, and some of its filaments frequently seem, at least 
in situation, to belong to the auditory nerve rather than to it. 

The nerve leaves the annular protuberance at about the centre of 
the space between the anterior and posterior edges of this latter, goes 
forward and outward to arrive at the internal auditory passage, through 
which it proceeds above and before the auditory nerve to the canal of 
Fallopius, which it exactly fills, and passes entirely through it. Its 
direction is consequently first outward and backward, then downward 
behind and above the cavity of the tympanum, and it emerges through 
the stylo-mastoid foramen, to be distributed in a considerable portion of 
the skin and of the muscles of the head. 

In its course along the canal of Fallopius, it gives off first down- 
ward and forward, a filament which reunites with the superior branch 
of the recurrent nerve given off by the second branch of the fifth pair, 
to form the superficial petrous nerve (JV*. petrosus superjicialis). 



(1) J.H.Meckel, De quinto pare nervorum cerebri, Gotting-en, 1748, for -the por- 
tion of the facial nerve contained in the Fallopian canal. — J. F. Meckel, Dissertation 
anatomique sur les nerfs de la/ace, in the M6m. de Berlin, vol. vii. 1752. — See also 
Bqck, Besekreibung dee funften Nervenpaar&s, Leipsic, 1817. tab. i. ii. 

(2) Gall, loc. cit., p. 206. 

Vol in. 8 



54 DESCRIPTIVE ANATOMY 

It then gives off a little downward and outward, behind the cavity 
of the tympanum, one or several filaments for the muscles of the little 
bones of the ear. 

A little lower, some distance above the stylomastoid foramen, it 
sends off a considerable branch, the cord of the tympanum {chorda 
tympani), which descends at first along the trunk, then goes outward 
and upward, passes through the posterior wall of the cavity of the 
tympanum, enters this cavity at the side of the pyramid, descends 
from behind forward between the malleus and incus situated on the 
former bone ; it anastomoses by one or more filaments with the tym- 
panitic nerves of the fifth pair, but gives no ramification to the mem- 
brane of the tympanum, leaves the tympanum through the fissure of 
Glaser, descends on the inside of the ascending branch of the jaw, and 
gradually becoming thicker, anastomoses at an acute angle with a 
twig of the lingual branch of the trifacial nerve which meets it. 

It does not seem to us probable, from our dissections, that the 
superficial petrous nerve and the cord of the tympanum, are only 
a filament of the fifth pair, which is fitted to the facial nerve, and 
which does not really anastomose with it,(l) although we consider 
the lower and prominent portion of the cord of the tympanum, as be- 
longing to the branch of the trifacial nerve. 

After leaving the stylo-mastoid foramen, the facial nerve gives off 
the following branches: 

1st. One single or double branch, termed the posterior, inferior, or 
deep auricular nerve (JV*. auricularis posterior, profundus inferior), 
which sends one or more inconstant filaments into the mastoid process, 
then goes upward and backward and divides into two branches, an 
anterior and a posterior, the former of which is the larger. 

The posterior, which sometimes forms the first branch of the facial 
nerve, ascends on the mastoid process, is distributed in the skin which 
covers it, extends to the occipitalis muscle, to which it distributes fila- 
ments, and anastomoses with the ramifications of the small occipital 
nerve. 

The anterior arrives at the lower and posterior part of the cartila- 
ginous portion of the auditory foramen, and of the external ear, sends 
some filaments to the skin of this region, and also to the posterior 
auricular muscle, and passing through the cartilage, is distributed in 
the integuments of the auditory passage. 

2d. The stylo-hyoid nerve (JV. stylo-hyoidcus) which is distributed 
partly in the upper portion of the muscles attached to the styloid pro- 
cess, and the posterior part of the digastricus muscle of the jaw, and 
partly sends several anastomosing filaments to the upper part of the 
ganglionnary nerve, and to the middle cutaneous nerve, given off by 
the third cervical nerve. 

3d. A branch termed the digastric (R. digastricus), which passes 
through the posterior belly of the digastricus muscle, and anastomose 

(1) Cloquet, Tr. d'anat., vol. ifc p. 610. 



OF THE NERVOUS SYSTEM, 00 

with the ramifications of the glosso-pharyngceal, the pneumo-gastric, 
and the accessory nerves. 

4th. Sometimes a filament which anastomoses with the posterior 
twig of the inferior auricular nerve, and with the filaments of the 
anterior branch of the third and fourth cervical nerves. This filament 
exists particularly when the inferior auricular nerve is small. 

After giving off these ramifications, the trunk of the facial nerve, 
passing under the ear, enters the parotid gland from above downward 
and from behind forward, assumes in this gland a direction which is 
oblique from below upward, still continuing to go forward, and forms 
within it a considerable plexus, the parotid plexus (plexus parotidevs). 
This plexus i formed by the nerve dividing at the posterior edge of the 
ascending branch of the jaw, into from two to five branches, which may 
always be referred to two which vary in direction and distribution. Of 
these branches, one is superior, the other inferior, and smaller than the 
former. They anastomose frequently together, and thus form a 
polygon convex forward, upward and downward, whence arise the 
other ramifications of the nerve, which are distributed in the 
skin of the upper, middle, and lower portions of the face, in that of the 
upper part of the neck and in most of the muscles of the face. 

Several considerable branches constantly unite posteriorly with this 
plexus ; they come from the superficial temporal nerves which arise 
from the third branch of the trifacial nerve, and which turn from be- 
hind forward on the posterior edge of the ascending branch of the 
jaw. 

By examining this plexus from above downward and from behind 
forward, we observe that it gives off some ascending, some anterior, 
and gome descending branches, which frequently anastomose together 
by intermediate twigs, equally distant from the edge of the parotid 
gland. 

I. ASCENDING BRANCHES. 

§ 1861. The ascending branches are the temporal and the malar 
nerves (JV. temporales et malares). Chaussier terms them collectively 
the temporo facial branch. 

a. Temporal ncrvca. 

§ 1862. We find, 

5th, 6th, 7th. Two or three temporal nerves, which give some small 
filaments to the parotid gland, ascend on the malar bone, anastomose 
between them with the superficial and deep temporal branches of the 
submaxillary nerve posteriorly, and with the frontal and lacrymal twigs 
of the first branch of the trifacial nerve, are distributed on the temporalis 
muscle, and send ramifications to the skin of the temples, to that of 
the anterior part of the external ear, the anterior auricular muscle, 



56 DESCRIPTIVE ANATOMT. 

and the external and upper part of the orbicularis palpebrarum 
muscle. 

When only two temporal nerves exist, the anterior is larger than 
the other. 

b. Malar nerves. 

§ 1863. 8th and 9th. These ave usually two nerves; they proceed 
more forward and upward than the preceding, and passing on the 
malar bone, they are distributed in the skin which covers this bone and 
the external edge of the orbit, in the outer part of the eyelids, in the 
external and lower part of the orbicularis palpebrarum muscle, finally 
in the posterior part of the zygomatici muscles. 

IL. ANTERIOR BRANCHES OR BUCCAL NERVES. 

§ 1864. There are usually three, more rarely two, anterior branches 
or buccal nerves (JV. buccales). 

The central one is the largest. 

They go almost directly forward on the upper and middle portion of 
the masseter muscle, beyond its anterior edge. The middle is situated 
directly on the excretory canal of the parotid gland. 

The superior, passing under the zygomatici muscles, to which it 
gives filaments, ascends towards the lower eyelid, and goes to the 
inner angle of the eye, where it often anastomoses with the infra- 
trochlear nerve given off by the fifth pair. 

The central divides into ascending and anterior twigs. 

The ascending twigs arrive at the lower part of the orbicularis 
palpebrarum muscle, the myscles of the sides of the nose, and the skin 
which covers them, anastomose with some filaments of the infraorbitar 
nerve which come from the fifth pair, particularly with the external, 
and terminate in the levator muscles of the upper lip, the orbicularis 
oris, and the skin of the upper lip. 

The inferior go directly forward, are distributed in the buccinator 
muscle, the skin of this region and that of the lower lip. They anas- 
tomose with the buccal nerve which comes from the third branch of 
the fifth pair. 

III. DESCENDING BRANCHES. 

§ 1865. The descending branches, ccrvico-faciales, Ch., arise from 
the lower and smaller trunk, which commonly anastomoses at its origin 
by some filaments with the superior. 

This trunk generally divides into two branches. 

The superior goes forward on the lower part of the masseter muscle, 
anastomoses with the inferior buccal nerve, and is distributed in the 
skin of the lower lip, the depressor labii inferioris, and the buccinator 
muscle. 



OF THE NERVOUS SYSTEM. *>» 

The inferior descends towards the lower angle of the jaw, and 
divides near the angle of this bone, into a superior and an infenor 
twi°". 

The superior twig, the marginal nerve (A*, marginalis), proceeds 
above and along the edge of the lower jaw, goes forward and upward, 
distributes its filaments in the muscles which depress the lower lip and 
in the skin of the chin, and anastomoses with the inferior labial nerves 
of the third branch of the trifacial nerve. 

The inferior divides in turn into two or three ramuscules, the su- 
nt rior cutaneous < ervical or submaxillary n rves ( JV. subcutanti colli su- 
periors), which descend under the jaw, are distributed in the upper 
part of the skin of the neck and in the platysma myoides muscle, and 
anastomose frequently with the ascending twigs of the anterior branch 
of the third cervical nerve. 

VII. EXTERNAL MOTOR NERVE. 

§ 1866. The external motor nerve, the sixth pair, the external oculo- 
muscular nerve (JV. oculo-muscularis externus, s. posterior, s. abducens, 
B.par sextum),{l) is flat, and arises by two very distinct roots, an 
internal and an external which is usually four times the size of the 
former, from the upper extremity of the pyramid, from the posterior 
edge and the posterior extremity of the lower face of the annular pro- 
tuberance, about two lines from the median line, and four or five lines 
inside of the facial nerve. From the inferior face of the annular protu- 
berance only the inner root generally arises, which sometimes does not 
extend to the posterior edge, but terminates two lines from this edge 
and arises only from the external face of this protuberance, although 
we cannot follow it farther either backward or forward. The ex- 
ternal root generally arises also from the anterior extremity of the pyra- 
mid. These two roots, particularly the internal, are formed of several 
fasciculi which are easily detached from each other. 

It is very rare that the internal root is the larger,(2) or that the 
filaments by which the nerve arises do not unite in two distinct roots. 

Sometimes the nerve arises only from the pyramid. Not unfre- 
quently it comes in part from the olivary body and the transverse band 
which is often found between the summits of the two pyramids. (3) 

We can, however, generally demonstrate particularly by compara- 
tive anatomy, that it arises from the medulla oblongata between the 
olivary bodies and the pyramids, much lower than it comes from them 
and that the different filaments coming from the olivary bodies, the 
small transverse striae, and the pons Varolii, are either supplementary, 
or as is true particularly of those from the annular protuberance, ap- 

(1) Zinn, Desc. oculi humani, Gottingen, 1755, tab. \i. .__,. K qq\ „k.„ wm 

(2) We have rarely seen this. Vicq-d'Azyr (Mem. de Parts, 1781, p. 589) observes 
also that this arrangement is rare. 

(3) Vicq-d'Aryr, Joe. cit., p. 589. 



58 DESCRIPTIVE ANATOMY 

pear to be distinct roots only because the fibres of the principal root of 
the nerve are separated from each other at their upper part by the pos- 
terior fibres of the pons Varolii.(l) 

The two roots generally unite before passing through the dura-ma- 
ter : sometimes, however, each passes through a special opening in 
this membrane and also proceeds three or four lines and even glides 
under a special fibrous bridge entirely distinct from the dura-mater 
before they join. In the cases where we have seen this arrangement 
it has always appeared on the left side alone, and the external fasci- 
culus was the smaller. 

These facts, compared with those adduced by Scemmerring, seem 
much in favor of the opinion that the ganglionnary nerve comes irom 
the centre of the nervous system, and that the cerebral nerves appear 
to be more numerous than they truly are by the enlargement of some 
branches. If proved that the external motor nerve always divides on 
the left side, it would be important on account of the analogy which it 
establishes with the vascular system. 

On leaving the encephalon the nerve becomes fibrous, is covered 
with a neurilemma and goes directly forward and outward, passes 
through the dura-mater below the posterior clinoid process, enters the 
cavernous sinus within which it is attended a shoit distance by the 
arachnoid membrane, being separated from the blood by the inner 
membrane of the sinus, and is situated on the outside of the internal 
carotid artery to which it is attached by compact cellular tissue. In 
passing above the anterior orifice of the carotid canal it anastomoses 
with the ganglionnary nerve by some filaments which form an acute 
angle with its trunk. Farther forward it communicates also by a fila- 
ment with the spheno-palatine ganglion, or the recurrent nerve of the 
second branch of the trifacial nerve. It goes to the orbit through the 
sphenoid fissure through a special opening in the dura-mater, enters 
this cavity between the fasciculi of the rectus oculi externus muscle, 
intimately united in this place with the common motor nerve and the 
nasal nerve of the first branch of the trifacial nerve, and coming on 
the inside of the rectus externus muscle is entirely distributed to it. 

The external motor nerve goes then only to one muscle. It very 
rarely gives off the nasal branch of the fifth pair,(2) but more fre- 
quently sends a filament to the opthalmic ganglion.(3) This latter 
arrangement makes the transition from that commonly found to the 
first. This anastomotic filament, however, undoubtedly belongs at 
least in part to the ganglionnary system. 

(1) Gall, loc. cit.,p. 204. 

(2) Otto, Seltne Wahrnehmungin, 1816, d. 108 

(3) Petit, Mem. de Paru, \T27. V 



Or THE NERVOUS BT8TEM. 59 



VIII. TRIFACIAL NERVE. 

§ 1867. The trifacial nerve, the fifth pair, (JV*. trigeminus, s. di- 
visits, s. mixtus, Gall, s. par quintum nervorum),(l) is very large : it 
app3ars about, six lines before the posterior edge of the inferior prolon- 
gation of the cerebellum, three behind the anterior edge of this prolon- 
gation, and nine from the median line of the pons Varolii. There it is 
manifestly composed of three more or less distinct roots, a posterior, a 
central, and an anterior. The posterior is situated farther backward 
and higher than the central, and the anterior below and on the inside 
of it. These roots were first correctly described by Santorini,(2) and 
after him by Wrisbeig,(3) Palletta,(4) and Niemeyer.(5) 

§ 1833. The central root is always much larger than the other two, 
for it is more than a line and a half in diameter after it emerges, while 
each of the others is only about half a line. Its fasciculi are more 
numerous : but they are smaller than those of the other two roots. 

At the place where it emerges it is a little depressed from above 
downward, but soon enlarges, becomes round, and again contracts. 

The fibres of the annular protuberance evidently separate at their 
base, so that we may judge from a superficial examination that the 
root does not arise in this place but from a deeper part. 

This middle root is composed of thirty or forty fasciculi of various 
sizes. The number of filaments which form these fasciculi is about 
one hundred : some authors assert less ; but they probably have de- 
scribed the fasciculi simply as filaments, or have neglected to decom- 
pose several of them. 

It is principally by following the central root that we can demon- 
strate very evidently that the nerve arises from a deeper part than 
where it leaves the annular protuberance. Santorini has stated per- 
fectly its true origin ;(6) his observations have been confirmed and 



(1) J. F. Meckel, De quinto pare nervorum, Gottingen, 1748. — A. B. R. Hirsch, 
Paris quinti nervorum encephali disquisitio anatomica, Vienna, 1765. — H. A. Wris- 
berg, Observationes anatomicae de quinto pare nervorum et de nervis, qui ex codem 
duram matrem ingredifalso dicuntur, Gottingen, 1777. — A. C. Bock, Beischreibung 
der fiinf ten Nerve npaares und seiner Verbindung mit andern Nerven, vorzuglich 
dem Gangliensystem, Meissen, 1817. — G. R. Treviranus, Sur les nerfs de la cin- 
quieme paire, consideres comme organes ou conducleurs dc sensations ; in the Journ. 
compl. du diet, des sc. med. vol. xv. p. 207. — Magendie, Sur les fonctions de la 
cinquieme paire de nerfs; in the Journ. de phy. exp., vol. iv. p. 176 and 302. 

(2) Obs. anat., Venice, 1724, p. 65. 

(3) hoc. cit. 

(4) De nervo crotophilico et buccina'orio, Milan, 1784. 

(5) De origine paris quinti nervorum cerebri, Hales, 1812. 

(6) Loc. cit., p. 65. The honor of this discovery then belongs to Santorini. 
Niemeyer seems to attribute it to Winslow, and is consequently wrong, for the 
Anatomy of Winslow appeared first in 1732, while Santorini's observations were pub- 
lished in 1724. 



00 DESCRIPTIVE ANATOMY. 

rendered still more exact by the labors of Winslow,(l) Scemmer- 
ring,(2) Gall,(3) and Niemeyer.(4) 

Here also the posterior part and the proper origin of the nerve are 
covered by the considerable development of the cerebral parts. On 
leaving the place where it appears, it enters from without inward, from 
before backward, and from below upward in the fissure of the central 
prolongation of the cerebellum, and is more or less completely divided 
into several cords by the transverse fibres of the annular protuberance, 
thus comes behind the union of the three peduncles of the cerebellum 
directly below the floor of the fourth ventricle, passes under the pos- 
terior prolongation of the cerebellum, almost the length of the external 
edge of the annular protuberance, and proceeds towards the groove 
between the restiform and the olivary bodies ; its strongest root arises 
there partly from the groove and partly from the olivary eminences. 

From this point to where it passes between the posterior and lateral 
prolongations of the cerebellum it is not fibrous, and is surrounded by 
gray substance ; but from this second point to its emerging from the 
annular protuberance it is formed of very apparent fibres, and is sur- 
rounded by a thin membrane. In its whole extent from its origin to a 
little before its emerging on the external face of the inferior prolonga- 
tion of the cerebellum it gradually becomes thicker, but before leaving 
the pons Varolii it slightly contracts and enlarges considerably after 
emerging. 

The fasciculi of the nerve are then more distinct and surrounded with 
neurilemma, and occupy the whole circumference of the pens Varolii. 
They enlarge partly by the separation and partly by the increase of 
their substance. When once emerged, the nerve is at first round but 
gradually becoming flatter, goes forward towards the upper end of the 
petrous portion of the temporal bone. At first it is loose in the skull, 
being loosely surrounded by a broad prolongation of the arachnoid 
membrane, but at the upper edge of the petrous portion of the temporal 
bone it enters a rounded and oblong sheath of the dura-mater -which 
generally is entirely separated from the cavernous sinus. This sheath is 
at first loose, but afterwards is placed strongly on its surface. It thus 
goes from before downward and from behind forward on the anterior 
face of the petrous portion of the temporal bone. 

In this course the trifacial nerve examined externally seems forned 
only by fasciculi placed one at the side of another. These fasciculi, 
however, communicate their whole extent by small intermediate fila- 
ments. Tins union and the ramification of fasciculi which results from it, 
become more and more marked from behind forward, and for about a line 
and a half to two lines the breadth of the fasciculi divide into very minute 

(1) Exp. anat., 1732, vol. iv. p. 1S2 

(2) Loc. cit., p. 267. 

(3) Ueberdas Organ dee Seele, Koenigsberg, 1796, p. 36. 

(4) LjOC. Ctt.f p. ill. 



OF THE NERVOUS SYSTEM. 61 

filaments, and interlace perpetually with each other near its anterior 
extremity. The trunk of the nerve which here touches outward the 
last curve of the internal carotid artery anastomoses with some fila- 
ments of the great sympathetic nerve. 

The anterior extremity of this large principal root suddenly differs 
in appearance from the other parts, and the different branches of the 
nerves. 

In fact at the anterior extremity of the upper face of the petrous 
portion of the temporal bone it forms a semicircular prominence, the 
concave edge of which is turned upward and backward and the convex 
edge downward and forward. This prominence which reaches be- 
yond the trunk of the nerve in every direction is six to ten lines long 
from before backward, one broad from within outward, and a line and a 
half high. It is termed the semilunar ganglion or gangliform plexus 
(ganglion semilunare, plexus ganglioformis, Vieussens ; intumescentia 
ganglio ajfinis, Scarpa ; plexus retiformis, Santorini ; icenia nervosa, 
Haller ; intumescentia semi-lunaris, Wrisberg ; Jigger lunatus, Neu- 
bauer ; Jlrmilla, Malacarne). It is transparent and reddish, and for 
about a quarter to half a line has no determinate texture, if we except 
some filaments which pass over its two faces, particularly the inner 
part of the inferior : but it then reassumes its fibrous appearance, so 
that in the mode directly the opposite of that over the plexus the fila- 
ments unite from above downward in larger threads, and thus produce 
fasciculi, still forming a trunk from one and a half to two lines broad, 
which immediately divides into three principal branches, the upper of 
which forms with the crural a very acute angle, and the latter a 
slightly obtuse angle with the posterior. The branches, the fasciculi 
of which still interlace with each other, are at first broad, but they 
gradually become round in approaching the openings through which 
they pass. 

The plexiform filaments of the nerve are not generally continuous 
with the inferior, but terminate in a channel grooved on the upper and 
concave edge of the ganglion. The inferior arise from all the circum- 
ference of the ganglion, and most generally extend to the upper and 
concave edge externally. The substance of the ganglion is homo- 
geneous internally, and precisely similar to that of the proper nervous 
ganglions. 

§ 1869. The small roots of the trifacial nerve do not contribute to 
form the prominence of the ganglion, although there is on the lower 
face of this latter, and of the large root, a groove formed by their pas- 
sage. 

The superior penetrates through a special fissure into the inferior pro- 
longation of the cerebellum from one fourth of a line to two lines dis- 
tant from the great middle root. When the two roots are very near each 
other they seem to enter through the same fissure : but in attentively 
examining we perceive this is rarely the case, even if it ever happens. 
The direction of the superior root in the inferior prolongations of the 
cerebellum is the same as that of the preceding, which proceeds below 
Vol. III. 9 



62 DESCRIPTIVE ANATOMY, 

it; we however cannot trace the former as far. Soon after emerging-, 
it turns on the upper face and the inner edge of the large root, arrives 
at its lower face, and continuing to pass on, it goes gradually outward 
where it reunites, after passing about half an inch, with the small in- 
ferior roots. It is formed of from three to six fasciculi of different sizes. 

The small inferior root is generally nearer the central than the su- 
perior, being often only a fourth of a line and seldom more than one 
line distant from it, and the rule mentioned by Palletta that they are 
always several lines distant cannot be admitted. They often evidently 
arise from the same groove. The part of the small inferior root which 
is contained in the cerebral substance always proceeds below the large 
in the same direction with it, and less distant from it than is the upper 
root. It is generally formed of a greater number of fasciculi than the 
upper, as there are about from six to eight. It leaves the annular 
protuberance on the lower face of the large root, and reunites with the 
small superior root in the manner stated, most generally, three or four 
lines behind the ganglionnary prominence of the large root. The trunk 
of the temporo-buccal nerve (IV. crotaphiio-buccinalorius), formed by this 
union, passes first under the large root, then under the ganglionnary 
prominence and the third branch of the fifth pair, thus goes outward 
and forward, and anastomosing in this course only by some inconstant 
filaments, first with this trunk, then with the third branch of the fifth 
pair, often but not always enlarges longitudinally under the plexiform 
ganglion, and after passing through the foramen rotundum of the ba- 
silar bone proceeds to form the temporal and buccal nerves. 

These two small roots form the small portion of the fifth pair, which 
is whiter and harder than the large. 

Their separation with the ganglion formed by the large portion is 
extremely curious^ as it presents a repetition of the formation peculiar 
to the nerves of the spinal marrow. 



A. FIRST PRINCIPAL BRANCH. 

§ 1870. The first branch, the superior or ophthalmic branch of the 
fifth pair (R. primus, s. superior, s. ophthalmicus), (1) is much smaller 
than the other two, and arises from the upper part of the ganglion. 
Its direction is from below upward and from behind forward on the 
outer side of the cavernous sinus towards the orbit, into which it pene- 
trates from within outward, on the outside of the common motor and 
below the superior motor nerve. 

In this course it gives off no branches, except nearer or farther from 
its origin a tolerably constant twig which unites to the superior motor 
nerve, and another less constant which goes to the ganglionnary nerve. 

(1) Rinn, Descriptw ociili humani, tab. vi.— Socemmerrins-, in Deniours Trailr 
des maladies des yeux, vol. iv., p. 32, pi. vi., fig-. 1. B "eniours, J ratio 



OP THE NERVOUS SYSTEM. 63 

But it is united in all its extent by very compact cellular tissue with 
the superior motor nerve. 

Just before entering the orbit it generally divides into two and more 
rarely into three twigs, which aie the nasal, the lachrymal, and the 
frontal nerves. In the first case, the second branch, which is larger 
than the other, is the common trunk of the lachrymal and frontal 
nerves. 

1st. The nasal or naso-ciliary nerve (N. naso-ocularis, s. naso- 
ciliaris), which in respect to size is between the other two, anasto- 
moses posteriorly with some filaments of the great sympathetic nerve, 
and divides into two branches generally before entering the orbit. 

The external branch (R. ciliaris, s. ad ganglion) is the smaller, and 
goes to the lenticular or ciliary ganglion (ganglion lenticulare, s. 
ciliare), which is situated on the outside of the optic nerve and forms 
its long root. Sometimes it anastomoses previously by one or two fila- 
ments with the common motor nerve.(l) It rarely gives off a ciliary 
nerve. 

The internal branch is larger and proceeds forward and inward on 
the optic nerve, with which it is connected. It not unfrequently gives 
off some ciliary nerves which proceed along the optic nerve to the eye 
and enter its capsule at its posterior part, proceed between the fibrous 
envelop and the choroid membrane to the iris, in which they are distri- 
buted with analogous but more numerous filaments which come from 
the lenticular ganglion, forming with them from five to ten nerves which 
generally divide again into two, more rarely into three fasciculi, which 
we shall describe when speaking of the eye. Several filaments from 
the ganglionnary nerve enter the ganglion. (2) 

The nerve then passes below the rectus oculi superior and obliquus 
major muscles, continues to proceed inward and forward, situated 
against the internal wall of the orbit, and soon divides into two 
branches, the ethmoidal and the infra-trochlear nerves. 

The ethmoidal or internal nasal nerve (N. ethmoidalis, s. nasalis, 
Winslow, s. ophthalmicus, Willis, s. nasalis internus), re-enters the 
skull through the internal and anterior orbitar foramen, afterwards 
emerges from this cavity through one of the anterior foramina of the 
cribriform plate of the ethmoid bone, proceeds to the nasal fossa, sends 
filaments to the mucous membrane of the superior turbinated bone and 
of the septum, sends others to that of the frontal sinus, then glides in a 
groove of the nasal spine of the frontal and of the proper nasal bones, 
descends along the anterior edge of the cartilaginous septum of the 
nose to the nasal fossae, emerges, and terminates at the tip of the nose 
sending filaments to its alee, at the end of which it anastomoses 

(1) Bock, loc. cit., p. 11. 

(2) Kibes, Sur quelques parties de Pail; in the Mem. dc la soe. mid. d'em., vol. 
vii., p. 86. — Bock, loc. cit., p. 12. 



64 DESCRIPTIVE ANATOMY. 

with some twigs of the second branch of the fifth and the seventh 

pairs.(l) . , 

The ethmoidal nerve sometimes divides into an anterior and a pos- 
terior trunk, the latter of which passes through the internal and pos- 
terior orbitar foramen, and remains in the nasal fossa.(2) 

The infra-trochlea^ or external nasal nerve (N. infra-trochlearis), 
advances below the rectus and obliquus superior oculi muscles, along 
the inner wall of the orbit, passes directly below the pully, and gives off 
a small filament to the mucous bursa in this place, leaves the orbit, and 
divides in the internal angle of the eye into two principal branches, a 
superior and an inferior. These branches soon subdivide into twigs by 
which the nerve is distributed in the tunica conjunctiva, the caruncula 
lachrymalis, the lachrymal sac, the orbicularis palpebrarum and the 
frontalis muscles, and the skin of the back of the nose. It anastomoses 
above with the supra-trochlear nerve, then with some filaments of the 
facial nerve, and farther forward with the second branch of the fifth pair. 

Sometimes the long root of the lenticular ganglion does not come 
from the nasal nerve, but from the third pair. Analogous to this ar- 
rangement but much more rare is the case where the nasal nerve 
comes from the sixth(3) and not from the fifth pair. 

2d. The frontal branch or nerve (iV. frontalis), the largest of the 
three branches of the ophthalmic nerve, proceeds between the other 
two from behind forward and from without inward on the levator pal- 
pebral superioris muscle directly below the arch of the orbit. It is at 
first intimately united with the superior motor nerve. 

At about its centre it sends off inward and forward a small branch 
which anastomoses with the infra-trochlear nerve, and which sends 
filaments into the frontal sinus, either directly, or indirectly by a small 
ganglion. 

It then sends off a larger filament, the supra-trochlear nerve (N. 
supratrochlearis), which proceeds along the internal wall of the orbit, 
passes above the pully of the obliquus major muscle, and emerges from 
the cavity of the orbit. This nerve, called also the internal frontal 
nerve, is reflected from below upward, distributes its twigs in the 
corrugator supercilii muscle, the internal and upper part of the orbicu- 
aris palpebrarum, the frontalis muscle and the skin which covers it, and 
anastomoses with some filaments of the infra-trochlear and the proper 
frontal nerve. 

The continuation of the trunk, the proper frontal nerve, gives off no 
branch within the orbit, leaves this cavity sometimes in one root but 
sometimes divided into several, through one or more supra-orbitar fora- 
mina, is soon reflected from below upward on the upper edge of the 
orbit, and is distributed in the skin of the forehead and the vertex. 

(3) Hunter, Observations on different parts of animal economy, London 1792 -A 
description of some branches of the fifth pair of nerves r 2fif; »**«**« 

(2) Bock, loc. cit., p. 13. ' *'" °- 

(3) Otto, Seltne Beobachtungen, Breslau, 1816, p. 108. 



OF THE NERVOUS SYSTEM. 65 

3d. The lachrymal nerve, (N. lachrymalis) which is between the 
other two in size, and is the most external of the three twigs of the 
first branch of the fifth pair, goes forward and outward, being also 
situated against the orbitar plate, and soon divides into an external 
and an internal branch. 

The external reunites with a twig of the subcutaneous malar nerve, 
which comes from the second principal branch of the fifth pair. From 
this trunk we generally see a filament depart which is sometimes 
double, and which passing directly to the anterior extremity of the 
inferior orbitar fissure, between the malar and sphenoid bones, goes 
outward in the temporal fossa, where it anastomoses with a malar 
branch of the facial nerve, more rarely with the superficial temporal 
nerve which comes from the second principal branch of the fifth 
pair.(l) 

This external branch sometimes sends a filament to the ciliary 
nerves, which come directly from the nasal nerve. (2) 

The internal branch divides into several twigs, which anastomose 
with each other like a plexus, and enter the lachrymal gland. 

These twigs are not distributed entirely in the gland. Some, after 
passing through it, come outwardly, where they are distributed, partly 
in the external part of the orbicularis palpebrarum muscle, partly in 
the integuments of the malar region, and anastomose with some fila- 
ments from the posterior branches of the facial, the frontal, and the 
subcutaneous malar nerves. 



B. SECOND PRINCIPAL BRANCH. 

§ 1871. The second principal branch of the fifth pair, the middle 
branch, the superior maxillary nerve (JR. quinti paris secundus, s. 
medius, s. JV. maxillaris superior),(S) is between the other two in 
its situation and volume. It arises from the anterior part of the gan- 
glionnary plexus ; it goes almost directly forward, or at least a little 
oblique from below upward, gives off no branch within the skull, 
although it sometimes anastomoses there with a filament of the gan- 
glionnary nerve, (4) and emerges from this cavity "outward and for- 
ward through the .great foramen rotundum of the sphenoid bone. It 
is flat, but after emerging it becomes round. 

Some distance from the place where it leaves the skull, the superior 
maxillary nerve gives off a small branch, the subcutaneous malar 
nerve (JV. subcutaneus mala), which reascends in the sphenomaxil- 
lary fissure. This branch enters into the orbit below the rectus ex- 
ternus oculi muscle, and anastomoses by one or more filaments with 

(1) Bock, loc. cit., p. 19. 

(2) Bock, loc. cit., p. 20. 

(3) J. P. Meckel, J)e quinto pare nervorum ; in Ludwig-, Opp. min., Gottingcn, 
1817.— A. Scarpa, Annot. acad., 1. ii., Modene, 1779. cap. iv. v. vi. tab. i. ii. 

(4) Laumonier, in Roux, Journ. de med., vol. xciii. p. 259. 



66 DESCRIPTIVE ANATOMY. 

the external twig of the lachrymal nerve. It sends off, farther for- 
ward, one or more ramifications, which enter into the lachrymal gland ; 
some of them remain in its tissue, while others, after passing through 
it, emerge from the orbit and are distributed in the orbicularis palpe- 
brarum muscle and the skin of the cheek, where they communicate 
with some filaments of the facial nerve and of the third principal 
branch of the fifth pair. Finally, the subcutaneous malar nerve 
emerges from the orbit through the malar foramen, sometimes in one 
trunk, and sometimes divided into several filaments. It is distributed on 
the face to the lower part of the orbicularis palpebrarum muscle, and 
also to the skin of the malar region, and communicates with the twigs 
of the facial and infraorbitar nerves. 

The superior maxillary nerve then divides into two much larger 
and nearly equal branches, which proceed almost directly from above 
downward. They are the pterygo-palatine and the infraorbitar 
nerves. 

The pterygopalatine nerve ( N. pterygo-palatinus) sometimes forms 
a single trunk, sometimes arises by two or three distinct filaments, 
which become, the roots of a small rounded triangular or cordiform 
ganglion, situated on the outside of the spheno-palatine foramen, and 
termed from its discoverer, the ganglion of Meckel (G. Meckelii),(\) 
and also the spheno-palatine ganglion (G. spheno-palatinum). The 
recurrent and palatine nerves come from this ganglion. 

The branches coming from the pterygo-palatine ganglion, vary ac- 
cording as the spheno-palatine ganglion does or does not exist. 

If it exists, the upper anterior nasal nerves partially arise from the 
trunk of the pterygo-palatine nerve, partly from the palatine nerve, 
and the naso-palatine nerve comes from the pterygo-palatine. 

Several small branches come from the trunk of the pterygo-palatine 
nerve, and from the spheno-palatine ganglion when they exist. 

First arises a filament which enters the sphenoidal sinus, or which, 
when it is very much developed, passes through this cavity and goes 
to the external motor nerve, with which it anastomoses ;(2) sometimes 
it sends ramifications to the sphenoidal sinus, and also to the posterior 
and most superior part of the septum of the nasal fossae. 

Next come four or five filaments which are a little larger; they pass 
through the dura-mater, which is extended on the pterygo-palatine 
foramen, are distributed in the mucous membrane which lines the pos- 
terior part of the upper and middle turbinated bones of the nose, and 
anastomose with the ramifications of the olfactory nerve. They are 
the upper anterior nasal or the spheno-palatine nerves (JV. nasales 
superiores et anterior es) . Farther on are the nerve of the septum, which 
will be described more properly after the naso-palatine nerve, and the 

(1) J. F. Meckel, Observation anatomique but un nceud ou ganglion du second 
rameau de la cinquieme paire des nerjs du cerveau nouvcllement decouvert avec 
Vexamen ghysiologique du veritable usage des nauds ou ganglions des nerf, ; in 
Mem. de Berlin, 1749. p. 84, 103. tab. m. 

(2) Bock, loc. tit., p. 26. 



OF THE NERVOUS SYSTEM. 67 

upper posterior nasal nerves, which, however, are more frequently 
branches of the recurrent nerve. 

The pterygo-palatine nerve then divides in the summit of the pterygo- 
palatine fossa, into a recurrent and a descending branch. 

The recurrent branch, the pterygoid or vidian nerve (JV. quinti re- 
currens, s. anastomoticus, s. pterygoideus, s. vidianus), is so termed 
from its direction ; for it goes backward, enters into the pterygoid fora- 
men, and anastomoses by several filaments with the facial and great 
sympathetic nerves. 

This nerve gives off first inward and downward, two or three fila- 
ments termed the posterior and superior nasal nerves (JV*. nasales pos- 
teriores superiores), which sometimes unite in a small trunk, termed 
by Bock, the pharyngeal nerve (R. pharyng&us). These nerves emerge 
sometimes through the lower part of the spheno-palatine foramen, 
sometimes pass through the inner wall of the pterygoid canal, penetrate 
inward through the pterygoid process, and are distributed in the pos- 
terior part of the mucous membrane of the nose, where they anas- 
tomose with the ramifications of the olfactory nerves in the muscles of 
the velum palati, the skin of the soft palate, and around the anterior 
orifice of the Fallopean tube. 

The external part of the nerve which is remarkable for its softness 
and reddish color, then divides, before leaving the pterygoid canal into 
two branches, which sometimes remain distinct to the ganglion, and 
by which it terminates. 

These two branches are the anastomotic nerves. The smaller 
superior or superficial nerve is the superficial petrous nerve (JV. 
petrosus superficialis). It proceeds generally single, seldom divided, 
through the fibro-cartilage, situated between the sphenoid bone and 
the petrous process, goes backward, upward, and outward, under the 
third principal branch of the fifth pair, in a groove on the upper face of 
the petrous process, leaves this groove and enters the Fallopian canal, 
anastomoses here with the facial nerve which passes through it, and 
sometimes sends filaments to the branches of the ganglionnary nerve 
which surround the upper part of the carotid artery like a plexus.(l) 

The inferior or deep, the larger, proceeds in the same direction as 
the recurrent nerve, emerges from the posterior extremity of the ptery- 
goid canal through the fibro-cartilage, between the sphenoid bone and 
the petrous process, goes outward and backward, passes' through the 
dura-mater, and goes into the carotid canal, where ii anastomoses with 
the upper extremity of the ganglionnary nerve, conjointly with a fila- 
ment of the sixth pair, thus forming a very constant and very evident 
anastomosis between the fifth pair and the great sympathetic nerve. 

The differences sometimes observed in this respect will be more in 
place in the description of the great sympathetic nerve. In fact, it is 
probably more correct to consider the deep branch of the recurrent 
nerve as a ramification of this latter. 

(1) Bock, loc. cit., p. 2B. 



68 DESCRIPTIVE ANATOMT. 

The descending branch or the palatine nerve (N. palalinus) is much 
larger than the recurrent, and is distributed to the middle and lower 
part of the mucous membrane of the nose, and also to the membrane 
of the palate. It is then more properly termed the naso-palatine nerve 
(N. naso palatinus.) 

From this, or from the spheno-palatine ganglion, or finally from the 
trunk of the pterygopalatine nerve, arises first the nerve of the septum 
of the nose (IS. septi narium), which Scarpa(l) less properly terms 
the naso-palatine nerve (N. naso-palatinus) .(2) 

This nerve enters the nose with the anterior and superior nasal 
nerves, through the spheno-palatine foramen, proceeds from without 
inward, passing before the sphenoidal sinus towards the septum on 
which it descends from behind forward, between the periosteum and 
the mucous membrane, to the anterior palatine foramina, farther for- 
ward on the left than on the right side, and thus arrives at the mem- 
brane of the palate. In passing through the palatine canal the nerves 
of the two sides unite, sometimes form a small prominence termed the 
naso-palatine ganglion (G. naso-palatinum), and expand on a promi- 
nence situated below the anterior palatine foramen. 

The palatine nerve then divides into a large anterior branch, the 
continuation of the trunk, and two or three smaller and posterior, all of 
which descend into the pterygo-palatine fossa. These branches are 
the great and small palatine nerves (iV. palatini major el minores). 
They sometimes arise directly from the ganglion, or even, as is true 
particularly of the smallest, from the second principal branch. 

From the anterior part of the great palatine nerve arise first the 
middle and inferior posterior nasal nerves (N. nasales posteriores medii 
et inferior es).(d) 

The posterior middle nasal nerve soon divides into two branches, 
which are sometimes separate at their origins. The superior goes 
directly forward in the mucous membrane of the middle turbinated 
bone. The second goes to the upper part of that of the inferior turbi- 
nated bone. 

The posterior inferior nasal nerve arises much lower, opposite the 
posterior extremity of the lower turbinated bone, towards which it pro- 
ceeds directly, and sends its filaments into the mucous membrane which 
lines the inner face of this bone anteriorly. 

These two nerves anastomose with the ramifications of the olfactory 
nerve. 

The anterior branch of the great nasal nerve sends directly back- 
ward a small twig, which passes through the pterygoid process in a 
special canal, and is distributed to the glandular substance of the soft 
palate. 

(1) Loc. cit., cap. v. De ncrvo palatine. 

(2) Scarpa, loc. cit., tab. i.— Hunter, Observations on different parts of the animal 
economy, tab. xvii. 

(3) Cloquet, loc. cit., vol. ii. p. 687. 



OF THE NERVOUS SYSTEM. 69 

The branch, the fasciculi of which separate from each other, goes 
forward and downward in the pterygopalatine canal, and comes 
through the posterior palatine loramen to the lower face of the bony 
palate, where it immediately divides into three or four considerable 
branches which proceed between the mucous membrane and the 
periosteum, along the inner face of the alveolar processes opposite the 
teeth, and are distributed in the gum. 

The two or three small palatine nerves descend behind the great 
palatine nerve, first in the pterygopalatine fossa, then lower in small 
special canals of the petrous portion of the temporal bone, on 
emerging from which, they enter into the amygdalae, the palato- 
staphylinus muscle, the muscular and glandular substance of the 
soft parts of the palate and the uvula. 

§ 1872. The infraorbitamerve (N. infraorbitalis), the second of the 
two branches in which the superior maxillary nerve divides, is di- 
rected from behind forward, from within outward, and from above 
downward, in the spheno-maxillary fissure, and goes to the infra-orbital 
canal. 

But before entering into this canal, it sends off a considerable 
branch called the dentar or posterior superior alveolar nerve ( R. den- 
talis, s. alveolaris posterior superior). This nerve divides sometimes 
even at its origin, sometimes afterward, into two branches, an anterior 
which is smaller, and a posterior which is larger. 

The posterior descends on the posterior part of the external wall of 
the maxillary sinus, below the temporalis muscle, which enters into 
this cavity through its posterior wall, is distributed in its mucous mem- 
brane,(l) and there anastomoses with the anterior dentar nerve. It 
terminates by some superficial ramifications which go to the buccinator 
muscle, and by deeper twigs which enter into small canals grooved in 
the posterior part of the body of the superior maxillary bone, and pene- 
trates into the roots of the three large posterior molar teeth. Each root 
receives one of them. We see one of them also between each two 
molar teeth, which goes into the gum. 

The anterior branch is distributed principally in the upper and pos- 
terior part of the buccinator muscle. 

After giving off the upper and posterior dentar nerve, the infra- 
orbitar nerve enters into the infra-orbitar canal. 

In passing through this canal it usually gives off, sometimes sooner 
and sometimes later, several branches, but always one at least, which 
is larger than the others even when they exist ; these are the anterior 
dentar nerves (N. dentales anteriores) which enter into the superior 
maxillary bone, send some filaments into the nose at the anterior part 
of the inferior turbinated bone, anastomose by several filaments with 
the posterior dentar nerves, pass forward on the roots of the anterior 
teeth, and terminate by ramifications which go to the incisors, the ca- 

(1) Bock asserts that the nerve is not distributed to the membrane of the maxillary 
Binus ; but we have several times clearly seen filaments arising from it. 

Vol. III. 10 



70 DESCRIPTIVE ANATOMT\ 

nine, and the anterior molar teeth, and to the gum. Those which be- 
long to theincisors and the canine teeth arise directly from the anterior 
dentar nerve ; those of the anterior molar teeth from the union of this 
nerve with the posterior dentar nerve. 

The infra-orbitar nerve then emerges from the canal through the 
infra-orbitar foramen, within which it divides into two principal 
branches, an internal and an external, and sometimes even in all the 
other subordinate branches. It thus comes on the face, where it 
divides into a considerable number of ramifications, which terminate in 
the skin and the muscles of the nose and upper lip, and anastomose 
with those of the first principal branch of the fifth pair, and also with 
some filaments of the facial nerve. 

The two principal branches usually subdivide into six or seven 
twigs, which may be distinguished into superior, anterior, and in- 
ferior. 

1st. Superior branch. There is usually only one superior twig, 
the inferior palpebral nerve (N. palpebralis inferior). This nerve, 
the first given off by the infraorbitar nerve, from which it is some- 
times separated even within this canal, and which often emerges 
through a special foramen situated more internally than the infra- 
orbitar, immediately ascends from without inward towards the lower 
part of the orbicularis palpebrarum muscle, and divides into an external 
and an internal twig. 

The external goes outward towards the external angle of the eye, 
on the lower part of the orbicularis palpebrarum, and gives off fila- 
ments to this muscle. It anastomoses with those of the internal twig, 
and with the temporal branches from the facial nerve. 

The internal goes to the inner angle of the eye, gives a twig to the 
skin of the nose which descends to the end of this organ, where it 
anastomoses with the nasal twig of the first principal branch of the 
fifth pair. It afterwards anastomoses in the lower eyelid with the 
external twig and with a filament of the infra- trochlear nerve, and ter- 
minates in the orbicularis palpebrarum muscle, the integuments of the 
lower eyelid, the caruncula lachrymalis, and the lachrymal sac. 

2d. Anterior or nasal twigs. The twigs which go forward, and 
also at the same time a little outward, are the superficial or cutaneous 
nasal nerves (N. nasales superficiales), which may be distinguished 
into an internal superior, and an external inferior. 

The internal superior, generally the smaller, is reflected upward 
under the levator palpebral superioris muscle, often gives origin to the 
preceding, and then divides into two or three filaments which proceed 
forward below this muscle along the centre of the nose, send their rami- 
fications into the levator labii superioris alaeque nasi, and the depressor 
alae nasi muscles, and the integuments of the middle and inferior parts 
of the nose. They extend to the back and tip of this organ, and anas- 
tomose in the latter place with the nasal twig of the first principal 
branch of the fifth pair. 



OF THE NERVOUS SYSTEM. 71 

The external and inferior descends under the levator labia snperioris 
muscle, often sends an ascending filament to the lower eyelid and to 
the lower part of the orbicularis palpebrarum muscle, then continues 
its course from above downward, often receives a filament from the 
preceding, goes forward to the ala of the nose above the levator labii 
snperioris aloeque nasi muscle, sends ramifications to this muscle and 
to the middle and upper parts of the orbicularis oris, and terminates at 
the lower part of the septum and of the top of the nose, where it anas- 
tomoses with the nasal twig of the first principal branch of the fifth 
pair. .' 

3d. Descending or labial twigs. The descending twigs are generally 
three or four superior labial nerves (2V~. labiates superior es), they suc- 
ceed one another from before backward. They are distinguished into 
internal, middle, and external. All descend from before backward, 
covered by the levator labii superioris muscle, are distributed in this 
muscle, the skin of the upper lip, the corresponding part of the orbicu- 
laris oris, and the lower part of the zygomatici and the buccinator 
muscles. They even penetrate through the orbicularis oris muscle, 
and go to the buccal membrane and the glands of the upper lip. 

3d. We frequently find also an external twig of the infraorbital 
nerve, the external palpebral nerve. This very small twig passes 
through the levator labii superioris muscle, goes outward, where some 
of its "filaments are distributed in the orbicularis palpebrarum muscle, 
and others anastomose with filaments of the facial nerve. 

C. THIRD PRINCIPAL BRANCH. 

§ 1873. The third principal branch, the inferior ox posterior branch 
of the fifth pair, the inferior maxillary nerve {R. quinti paris tertius, s. 
inferior, s. posterior, s. nervus infra-maxillaris),(l) which is by far the 
largest, 'arises from the lower and posterior part of the ganglionnary 
plexus, and is formed principally by the small anterior portion, whence 
Palletta(2) considers it a distinct nerve. It is the shortest of the three 
within the skull, and goes from above downward, and slightly also 
forward and outward, and enters the round foramen of the sphenoid 
bone, after anastomosing in this course with some inconstant filaments, 
with' the cavernous ganglion of the sympathetic nerve. (3) 

The inferior maxillary nerve is distributed to the muscles, the in- 
teguments, and the teeth of the lower jaw, the lower lip, the lower 
salivary glands, and the tongue. 

It is covered where it emerges from the cranium, by the pterygoideus 
externus muscle, and soon divides into two large branches, an upper 
and anterior, and a lower and posterior. This bifurcation however is 

(1) A. F. L. Fitzau, De tertio ramo paris quinti nervorum cerebri s. nervi ma.nl- 
lari inferiori, Leipsic, 1811. 

(2) Denervis crotaphiticoctbuccinatorio, Milan, 1784. _ 

(3) Laumonier, loc. cit.— Munniks, Dc origine ncrvi intercost. m Obs. rar., trro- 
ningen, 1805. 



72 DESCRIPTIVE ANATOMY. 

not constant, for sometimes the twig formed by the two branches 
comes directly from the trunk. 

§ 1874. The upper anterior branch is much smaller than the other, 
divides soon after and even before emerging from the skull, into five 
twigs, which separate from each other like rays. They are the mas- 
seteric, the internal and external deep temporal, the buccal and the 
pterygoid nerves. 

The masseteric nerve (iV. masselericus), the most external, which 
generally arises the highest, pursues a transverse direction from within 
outward, directly before the articular surface of the temporal bone, on 
the outside of the pterygoideus externus muscle, where it sends fila- 
ments to the ligaments of the temporo-maxillary articulation, and to 
the lower part of the temporalis muscle, then descends from within 
outward between this muscle and the pterygoideus' externus muscle, 
goes to the sigmoid fissure of the lower maxillary bone, and passing 
behind the tendon of the temporalis muscle, glides between the two 
layers of the masseter, in which it is almost entirely distributed. 

The second twig, the external deep temporal nerve (N. temporalis 
profundus externus), arises farther forward and inward, often comes 
from the preceding or from the buccal nerve, and sometimes from a 
common trunk with the following. It goes outward under the ptery- 
goideus externus on the temporalis muscles, commonly anastomoses 
with the following and by an intermediate filament, and goes imme- 
diately upward and inward to enter the-temporalis muscle. 

The third twig, the deep internal temporal (iV. temporalis profundus 
internus), is generally larger than the preceding, and follows the same 
course. It is distributed also in the temporalis muscle, but also sends 
some anastomotic filaments to the buccal nerves. It also gives off 
others farther forward which go to anastomose with the cutaneous 
malar and with the lachrymal nerve on the outside of, and sometimes 
even within, the orbit : the existence however of these last two anas- 
tomoses has been doubted, since the researches of Bock, who regards 
the filaments generally considered as such, as ramifications of the 
arteries.(l) 

The fourth twig, the buccinator or buccal nerve (N. buccinalorius), 
is usually the largest of the five, and sometimes the trunk of the three 
preceding. It goes forward between the two pterygoidei muscles and 
through the external, sends filaments to these two muscles, particu- 
larly the external, arrives at the lower part of the temporalis muscle, 
then descends between this latter and the pterygoideus externus, comes 
on the external face of the buccinator, is distributed mostly to this 
muscle, passes through it to send some filaments to the membrane 
and to the buccal glands, anastomoses with the anterior branches of 
the facial nerve, and terminates in Ihe levator and depressor anguli 
oris muscles. 

I l ) Horlc, lor. cit., p. 44. 



OP THE NERVOUS SYSTEM. 73 

The fifth twig, the pterygoid nerve (N. pterygoidtus), is the 
smallest. It arises from the inner part of the superior branch, passes 
between the pterygoideus exterrms and peristaphylinus muscles and 
arrives at the upper part of the pterygoideus internus, to which it is 
entirely distributed. 

§ 1875. The posterior and inferior branch is much larger than the 
preceding and the proper continuation of the trunk, divides soon after 
arising into three twigs, the superficial temporal, the inferior dentar, 
and the lingual nerve. 

The superficial temporal nerve (JV*. temporalis superjicialis) most 
generally arises by two more rarely by three roots, and still more rarely 
by one. Of these two roots, the inferior, the smaller, comes from the 
inferior dentar nerve and reunites with the superior, so that the sphero- 
spinous or middle cerebral artery passes between them. 

The trunk goes from within outward on the inside of the temporo- 
maxillary articulation between the condyle of the jaw and the lateral 
ligament, and here divides in five or six branches. Two or three of 
these branches penetrate from without inward and from behind for- 
ward in the parotid gland, and anastomose with this trunk and with 
some ramifications of the facial nerve. One or two of the others, 
which may be termed the nerves of the external auditory passage (N. 
meatus auditorii externi inferior, s. superior), go backward, pass 
through the anterior wall of the osseous portion of the auditory pas- 
sage, and pass between this and the cartilaginous portion; Their rami- 
fications are distributed some in the integuments of the inner part of 
the external ear, and others in those of the auditory passage. We 
see also one of them which goes to the membrane of the tympa- 
num, glides between its two layers, and anastomoses by one or two 
filaments with the cord of the tympanum.(l) 

The last and largest branch of the superficial temporal nerve passes 
through the parotid gland to the external ear, and terminates in the 
integuments of the central part of the cranium by anastomosing with 
some filaments of the great occipital and the frontal nerve of the first 
principal branch of the fifth pair. It also communicates with some 
filaments of the external lachrymal twig and of the cutaneous malar 
nerve which go outward. 

The other two nerves given off by the posterior and inferior branch 
of the infra-maxillary nerve at first form only a single but very short 
trunk. 

The inferior dentar nerve (N. alveolaris maxillai inferioris, N. 
maxillaris inferior), which is situated between the other two twigs of 
the posterior branch which is generally the largest ramification given 
off by the trunk of the inframaxillary nerve, sometimes arises by two 
roots which embrace the internal maxillary artery. It descends from 
within outward and from behind forward, first between the two ptery- 

(1) Bock, lor. cit., p. 49. 



74 DESCRIPTITE ANATOMY. 

goidei muscles, then between the external and the condyle of the jaw. 
Near its origin it gives off a small and very constant branch, the mylo- 
hyoid nerve (N. mylo-hyoideus), which descends from behind forward 
in a channel grooved in the inner face of the branch of the jaw, sends 
a twig to the submaxillary gland, goes towards the lower face of the 
mylo-hyoideus muscle, proceeds from behind forward between this 
muscle and the anterior belly of the digastricus, gives some filaments 
to both of them but particularly to the mylo-hyoideus muscle, and after 
being reflected from below upward on the lower edge of the lower 
jaw, is distributed in the muscles of the chin. 

The trunk of the inferior dentar nerve proceeds from behind forward 
in the inferior dentar canal. But it generally divides on entering into 
two branches, a superior which is smaller, the dentar nerve (N. den- 
talis), and an inferior and larger, the mental nerve (R. mentalis) ; these 
proceed at the side of each other, and communicate by numerous anas- 
tomosing filaments. 

The dentar branch is situated below the teeth, and sends a filament 
to each of them and to each root of the molar teeth. All these fila- 
ments arise farther back than the teeth to which they proceed : be- 
tween each two teeth it sends a filament to the gum. 

The mental branch emerges through the mental foramen. It soon 
divides under the levator anguli oris muscle into two twigs, the infe- 
rior labial nerves (N. labiates inferiores), the internal of which is larger 
in a greater or less degree than the external; 

The direction of the external is upward ; it sends some filaments to 
the levator anguli oris muscle, but principally to the lower part of the 
orbicularis oris, the glands of the lower lip and the buccal membrane, 
and anastomoses with some filaments from the inferior branches of the 
facial nerve. 

The internal, covered by the depressor labii inferioris muscle, goes 
forward and upward, sends filaments to this muscle, to the levator 
menti, the central part of the orbicularis oris, the skin of the chin, the 
glands of the lower lip, and the buccal membrane, and anastomoses 
with the marginal branch of the facial nerve. 

The lingual nerve (N. lingualis, s. gustatorius) , the most anterior of 
the three twigs of the lower and posterior branch of the inframaxillary 
nerve is between the other two in respect to size. It arises farther 
inward than they, and is frequently united to a considerable extent in a 
common trunk with the preceding. It descends with it from behind 
forward, usually on the inside of the internal maxillary artery, sepa- 
rates from the inferior dentar nerve and goes inward, receives before 
the palatostaphylinus and pterygostaphylinus muscles, and behind the 
pterygoideus externus, the cord of the tympanum, which unites with it 
at a very acute angle, then passes before the inferior dentar nerve, some- 
times sends to the pterygoideus internus muscle a filament which is 
often detached above the anastomosis with the cord of the tympanum, 
enters between the pterygoideus internus and the ascending branch of 
the jaw, and passing above the submaxillary gland, gives to iLas high 



OF THE NERVOUS SYSTEM. 



75 



as the angle of the jaw several considerable filaments, which come 
sometimes directly from its trunk, sometimes from a small ganglion 
which it forms on it, and which is called the maxillary ganglion (gan- 
glion maxillare.) 

These filaments are distributed principally in the gland. Generally 
however one of them emerges from it, descends on the hyoglossus 
muscle, anastomoses with a branch of the lingual nerve, and termi- 
nates in the genio-glossus muscle. 

The trunk of the lingual nerve then goes forward between the hyo- 
glossus and mylo-hyoideus muscles, passes between the sublingual 
' gland and the hyoglossus muscle having before it the excretory duct 
of the submaxillary gland, anastomoses by several considerable fila- 
ments which come from its inner side with the hypoglossal nerve, sends 
some which are very minute to the buccal membrane and larger ones 
to the sublingual gland, and divides into seven or eight branches which 
proceed from behind forward and from below upward between the 
styloglossus and genio-hyoideus muscles. These branches separate 
like the sticks of a fan, and go principally to the edges and tip of the 
tongue and are there distributed by minute filaments in the skin 
of this organ. 



IX. INTERNAL MOTOR NERVE. 



§ 1876. The superior or internal motor nerve, the pathetic, the 
fourth pair, the internal oculo-muscular nerve (N. oculo-muscularis su- 
perior, s. minimus, s. musculi oculi obliqui superioris, s. par cerebrate 
quartum, s. N. patheticus),(l) the smallest cerebral nerve, generally 
arises by an anterior and a posterior root, each composed of one fila- 
ment about the same size. They are frequently half an inch apart, 
but united by cellular tissue. They arise directly behind the external 
half of the posterior part of the tubercula quadrigemina from the an- 
terior and external part of the upper face of the cerebral valve, so that 
the anterior arises from some transverse medullary fibres which cover 
the valve in this place, and which unite them on the median line with 
those of the opposite side. This nerve seldom has three roots and still 
more rarely one only. 

After arising, it goes downward and a little forward, first on the 
upper extremity of the anterior prolongations of the cerebellum, then 
about two lines from the anterior edge of the occipital protuberance, 
first on the lateral and then on the lower face of the cerebral peduncle. 
After proceeding much farther within the skull than any other ence- 
phalic nerve, it comes to the posterior clinoid process. There it enters 
into a special canal of the dura-mater, the internal wall of which is 
very thin and separates it from the cavernous sinus, usually anasto- 
moses there with the first branch of the trifacial nerve by a small fila- 

I 1 ) Zinn, loc. cit.— Sccmmerring-, in Demours, loc. tit., vol. iv. p. 31, pi. vi., fig. 1. 



76 DESCRIPTIVE ANATOMY. 

merit, and is situated first below the common motor and the ophthal- 
mic nerves. At the sphenoidal fissure it is situated above the first af 
these two nerves, enters into the orbit through the upper and internal 
part of this fissure, and its direction there is from behind forward and 
from without inward directly under the periosteum, attended by the 
frontal twig of the ophthalmic branch of the fifth pair, and enlarges 
much in this course. Finally it enters the obliquus oculi superior 
muscle at about its centre. 



X. COMMON MOTOR NERVE. 

§ 1877. The common motor nerve, the common motor of the eye, the 
third pair, the common oculo-muscular nerve (N. oculomuscularis in- 
ferior, s. medius, s. ocido-motorius communis, s. par tertium),{\) a con- 
siderable trunk generally the fourth in size and rarely the third among 
the encephalic nerves, arises about two lines before the anterior edge 
of the annular protuberance on the inner face of the cerebral peduncle 
about two lines above its lower edge, at the place where the gray 
cribriform plate which covers the inner face of the peduncle com- 
mences. It even arises in great part from this layer. Some smaller 
filaments coming from near the internal edge of the lower face of 
the cerebral peduncle usually join this root, which is single and very 
large. 

It is however easy to follow the origin of the nerve farther upward 
and backward, for beyond the point where it leaves the annular pro- 
tuberance it is covered anteriorly only by a very thin layer of gray 
substance of which we perceive no trace posteriorly. "When this sub- 
stance is removed, when the annular protuberance is divided, turned 
from above downward, and carefully cut longitudinally on the median 
line, we observe that a medullary layer commences at the place where 
the nerve emerges, continues with its fibres, and terminates like a fan 
upward and a little forward, forms a fasciculus which is rounded pos- 
teriorly although straight at first, and curves from below upward. 

The anterior and flat part of this layer extends to the bottom of the 
groove existing between the two cerebral peduncles. Its posterior 
parts are arranged in fasciculi, converge from before backward, and 
are blended at their posterior part. The anterior part is loose, but in 
order to see the posterior we must separate the anterior half of the 
annular protuberance and turn over the two folds. The posterior part 
of this medullary layer then rises directly below the floor of the aque- 
duct of Sylvius. 

The two nerves are at first attached to each other by their inner 
faces, so that they slightly resemble the arrangement of the optic 
nerves. After leaving this point, where they are detached from the 
encephalon, they proceed from within outward and from before back- 

(1) Zinn, loc. cit.— Scemmerring, in Demours, he. cit., vol. iv. p. 34, pi. vi. fig. 2 



OF THE NERVOUS SYSTEM. 77 

ward, arrive at the external wall of the cavernous sinus, are situated 
within and above the first branch of the trifacial and the superior motor 
nerves ; then changing this direction below and on the outside of these 
nerves they pass through the dura- mater which closes the sphenoidal 
fissure, and enter the orbit with the external motor and the nasal branch 
of the trifacial nerve. 

Before passing through the dura-mater, the common motor nerve is 
divided into a superior and an inferior branch. 

The superior, the smaller, goes inward and forward, passes on the 
optic nerve and the nasal twig of the ophthalmic branch, anastomoses 
with this latter, sends its twigs into the rectus oculi superior muscle, 
and passes through it to be distributed in the levator palpebral superi- 
oris muscle. 

The inferior is much larger than the preceding, and passes below 
and on the outside of the optic nerve, between it and the rectus oculi 
inferior muscle. It usually divides into three twigs, an internal, which 
is larger, which goes to the rectus internus muscle ; a middle, which 
is shorter, for the rectus inferior muscle, and an external inferior 
branch, which is the longest and thinnest, and which goes to the ob- 
liquus inferior muscle, and the lenticular ganglion. 

This latter gives off near its origin a short filament, which, situated 
on the outside of the optic nerve, goes to the posterior extremity of the 
lenticular ganglion, and forms its short root. This filament is always 
composed of several threads, arises more rarely from the lower branch, 
but sometimes also it comes at the same time from the external twig, 
from the middle, and even from the trunk of the lower branch.(l) 

Sometimes, but very rarely, the long root of the lenticular ganglion 
also arises from the common motor nerve. (2) 

XI. OPTIC NERVE. 

§ 1878. The optic or ocular nerve, the second pair (N. opticus, s. 
visorius, s. par secundum), the largest of the encephalic nerves arises 
by a broad and flat portion from the posterior part of the external face, 
and also from the upper face of the optic bed and the tubercula quad- 
rigemina. Its anterior part, which is the broadest, leaves the upper 
face of the optic bed, from the substance of which it is easily dis- 
tinguished on account of the transverse direction of its medullary 
fibres, to pass on its anterior and external tubercle. The posterior 
passes below the posterior and external tubercle, and is attached in 
this place to the tubercula quadrigemina, particularly the posterior, by 
a medullary band, which goes forward from these latter, passing below 
the posterior and external tubercle of the optic bed. Thence the optic 
nerve proceeds from behind forward and from without inward, and de- 
scends on the lower face of the cerebral peduncle, with which it is so 

(1) Bock, loc.eii., p. 12. 

(2) Morgragni, Ep. ariat., xvi.l 59.— Meckel, De quimopare, §48. 
Vo*. III. 11 



78 DESCRIPTIVE ANATOMY. 

closely connected that we must admit that it partly arises from this 
prolongation, although separated from it in almost all its extent by the 
pia-mater. It gradually becomes narrower, but thicker and more 
rounded, and unites at an obtuse angle with that of the opposite side 
on the median line, on the lower face of the cerebrum, below the floor 
of the third ventricle. The union is so intimate that the two nerves 
form only one medullary mass. This mass itself has the form of an 
elongated square, which differs in different subjects, as is indicated 
in Morgagni(l) and Wenzel,(2) nor has it always the same volume. (3) 
It receives above some medullary fibres from the floor of the third ven- 
tricle, so that we are authorized to think that the optic nerve partially 
arises from this point. 

After this union the two optic nerves separate and go forward and 
outward. Hence, when we view their place of union and their an- 
terior and posterior parts, they represent the form of an X or of a cross. 
Thus, their decussation has been termed the intercrossing (chiasma). 
It is very rare, and perhaps never the case, that the two nerves do not 
unite, (4) or that by an arrangement, perhaps the opposite of the pre- 
ceding, a small pointed protuberance comes from the anterior edge of 
the decussation.(5) 

Opinions vary in regard to the manner in which the optic nerves 
unite. Some assert that they are only fitted to each other,(6) others 
that they entirely intercross, and that of the right eye, for instance, 
passes to the left side of the body behind the decussation. (7) Finally, 
some think that there is only a partial decussation, an intercrossing of 
most of the fibres,(8) that the external fibres of each nerve are situated 
on the same side of the body before as behind the decussation, while 
the internal intercross with the corresponding fibres of the opposite 
side, and pass to the other side of the body. (9) 

Those who maintain the first hypothesis, assert, 

1st. That on examining the decussation in the recent state, the 
fibres of the nerve are seen to pass through its external edge, but do 



(1) Ep. anat., xvi. § 13. 

(2) Depenit, struct, cerebri, p. 110. 

(3) Ibid. 

(4) Vesalius, Decorp. hum. fab. 1. iv. c. iv. 

(5) Scemmerring, in Ncethig, De decussatione nervorum opticorum, Mayenee, 
1780. 

(6) Gallen, De util. part., lib. x. c. xii. — Also a great number of his successors, 
mentioned in Ncethig.— Zinn, Desc. oc. hum., Gottingen, 1765, p. 190. — Vicq-d'Azyr, 
in the Mem. de Paris, 1781, p. 554.— Meckel, in Halter, Grundriss, p. 386. 

(7) This opinion wa3 supported before Galen, as he refutes it (loc. cit.) ; those who 
have defended it since, are cited by Morgagni (Ep. anat.) and by Scemmerring, in 
Ncethig, loc. cit., and Denksder Miinchner Akad.. 1808, p. 60. 

(8) Michaelis, Ueber die Uurchkreuzung der Schnervcn ; in Grosse, Magazin zur 
Naturgeschichte des Menschen, vol. ii. part i. p. 149. 

(9) Ackermann, in the Med. bibl. of Blumenbach.— Wenzel, Locus unionis ner- 
vorum opticorum ; in De pen. str. cereb., cap. xi. p. 109. 



OF THE NERVOUS SYSTEM. 79 

not leave their side, while the middle part is absolutely homogeneous, 
and presents no trace of fibrous structure^ 1) 

2d. That the two optic nerves have been found entirely distinct from 
each other, and the sight was unimpaired. (2) 

3d. That where the optic nerve wasted after the loss of an eye, the 
change in the texture was seen only in the nerve of the same side, be- 
hind the decussation,(3) and that it is very easy to distinguish in this 
latter the two nerves from each other, by their color and other proper- 
ties.^) 

The partisans of the second opinion state, 

1st. The normal appearance. (5) 

2d. Those cases where the origin of one optic nerve, or the part of 
the two nerves behind the decussation has been found unusually large 
or small, and the nerve of the opposite side presented the same charac- 
ter before the decussation, (6) while the sight was unaffected. 

3d. The cases in which the disease of the nerve before the decussa- 
tion extended behind it only to the nervous cord of the opposite side, 
and affected even the corresponding cerebral portions of this side. (7) 

4th. The analogous cases where the origin of one of the two nerves 
was affected, and the functions of the eye of the opposite side were 
deranged. (8) Sometimes only this origin was diseased, and not the 
portion of the nerve on the other side of the decussation. (9) 

5th. The analogy with several animals, particularly with most 
fishes, the nerves of which evidently intercross and enter each other. 

The third hypothesis is supported, 

1st. By the anatomical examination of the parts in the normal 
state. (10) 



(1) Vicq-d'Azyr, loc. cit. — Wenzel, p. Ill, 115. This anatomist admits that a 
small portion of the inner part proceeds to the opposite side before they unite ; but 
as he expressly remarks that he has been unable to discover any fibre in this in- 
ternal part, the preceding- sentence does not favor the decussation, since the direc- 
tion he allows to the fibres is only that of the whole nerve. — Caldani (Mem. delle 
soc. ital., vol. xii. part ii. p. 28) has found the optic nerves united behind the decus- 
sation by a transverse medullary band. 

(2) Vesalius, loc. cit. — Nicolas de Janua, in Caldani, Opusc. anat., Padua, 1803, 
p. 40. 

(3) Vesalius, loc. cit. — Cesalpino, in Riolan, Anthopogr., 1. iv. — Cheselden, in the 
Phil, trans. — Santorini, Obs. anat., c. iii. p. 63, 64. — Meckel, in Haller, Grundriss, 
p. 386. — Caldani, Opusc. anat., p. 33 and 35: two cases. — Id.,' in Mem. delle soc ital., 
vol. xii. plate ii. p. 27.— Burns, Anatomy of the head and neck, Edinburgh, 1811, 
p. 359. 

(4) Santorini, loc. cit. 

(5) Petit, in the MSm de Paris, 1736, p. 7. — Scemmerring, loc. cit. 

(6) Scemmerring 1 , loc. cit. Several cases. 

(7) Michcelis, loc. cit., p. 145. — Caldani, loc. cit., p. 35. — Wenzel. 

(8) Valsalva, in Morgagni, Ep. anat., xiii. p. 115. obs. iii. 

(9) Wenzel, loc. cit., p. 125. 

(10) Caldani, Opusc. anat., p. 37. tab. ii. fig-. 4. The simple maceration in water, 
or immersion in sulphuric acid and vinegar, gave no result ; but this is not the 
case with nitric acid after the neurilemma was removed. Caldani has observed, 
eight times in this manner, that the external nervous fibres went directly to the eye 
of the same side, and the internal to that of the opposite side, that consequently these 
latter intercrossed, and that even the fasciculi visibly divided into several branches. 



SO DEScniPTIYE ANATOMY. 

2d. By those pathological cases where one eye being destroyed and 
its nerve affected, the external fibres of the diseased nerve and of the 
healthy nerve, remained each on their side before and behind the de- 
cussation, while the internal fibres of the healthy eye passed through it 
to go to the opposite side, where they formed the internal fibres of the 
nerve of this side, and the internal fibres of the diseased nerve also 
passed to the healthy side, although less evidently, at least in some 
cases.(l) 

3d. By the cases, where after the disease of an eye and of its optic 
nerve, the decussation and the nerve of the same side behind it, were 
wasted. (2) 

4th. By the cases of the loss of an ej T e with the affection of only 
one optic nerve before the decussation and of the opposite nerve, or of 
both, behind this point. (3) This^fact really seems to favor the hypo- 
thesis of a partial decussation, since different physiologists think it 
cannot be explained otherwise, and more so, because in many cases 
where the two nerves were wasted behind the decussation, that of the 
healthy eye was found unusually large. (4) 

When all these pathological facts are duly considered, we must 
admit that they do not prove positively either of the three opinions, in- 
asmuch as the dissection of the healthy parts has not demonstrated 
the fact of the decussation. In fact, they may be explained satisfac- 
torily by saying that the substance of the two nerves is so blended in 
the decussation, that these nervesdonot partially or wholly cross, and still 
less are they placed one against the other, but they properly arise from 
this common substance formed by the union of the two optic bands 
(iracius optici), which opinion differs much from that of a partial de- 
cussation. The differences of the pathological phenomena, authorize 
the adoption of this hypothesis, as this alone explains them very well. 
We may then consider as accidental, that where the optic nerve is 
diseased to the decussation, the alteration is observed on the other side 
of this union, on the cord of the same side, on that of the opposite side, 
or on both at once. This intimate union of the two portions of the 
optic nerves between their origin and decussation, is rendered very 
probable by what we have remarked, and which had been seen before 
us by Morgagni,(5) Michaelis,(6) Bichat,(7) and Wenzel,(8) that 
when the optic nerve had wasted and had been gray for a long time 

Wenzel ha9 once found in a subject whose sight was not affected, some gray sub- 
stance in the centre of the decussation ; the internal fibres of the two nerves evi- 
dently passed through this substance to intercross (loc. cit., n. 118). 

(1) Wenzel, 113, 217. 

(2) Walter, Uebcr die Einsavgvng -and die. Durchkreuzunsr der Sehnerren, 
Berlin, 1794, p. 97. B 

(3) Ackermann, loc. cit.— This has been seen in most cases. 

(4) Morgagni, Epist. anat., xviij. 40.— Michselis, he. cit., p. 145.— Wenzel, p. 125. 

(5) Epist. anat., xviii. 40. 

(6) Loc. cit., p. 146. 

(7) Anat. descript., vol. iii. p. 153. 

(8) hoc. cit. p. 112. 



OF THE NERVOUS SYSTEM. ^ 81 

either before or behind the decussation, the decussation itself and the 
portion of the nerve before or behind it, was not in the least abnormal, 
and when the contrary occurred, the portion separated by the decus- 
sation from that first affected by the disease, was always altered much 
less than this latter. This phenomenon certainly indicates a great 
difference and a marked distinction between the posterior part of the 
nerve, including the decussation and the anterior portion, and the more, 
as when the portion situated before or behind the decussation is dis- 
eased, it usually presents the same kind of alteration in all its extent. 

The differences between the pathological phenomena, mentioned by 
us above, depend perhaps on primitive differences of structure. This 
conjecture seems much more probable, as the structure of the nervous 
system, notwithstanding its great regularity, nevertheless frequently 
presents, when attentively considered, very great anomalies. It is 
then possible, that as in other organs situated on the median line, the 
union is sometimes more, sometimes less intimate, sometimes there 
is merely a juxta-position, and that there are a series of successive 
states, the first link of which is the case described by Scemmerring, in 
Noethig, and the last, that mentioned 1 by Vesalius, although Haller 
rejects this hypothesis.(l) 

Finally, the texture of the optic nerve before or behind the decussa- 
tion, according as the origin of the merve or the eye are primitively 
affected, proves nothing in favor of either of these three opinions, since 
in some cases where the sense of vision was lost in both eyes at the 
same time, one of the nerves was much thinner than the other behind 
the decussation. (2) 

Finally, according to our own observations, this partial decus- 
sation is very probable ; some at least of the differences in the patholo- 
gical phenomena may then be easily explained, since, when the inner 
part of the optic nerve is affected, that of the opposite side, and when 
the outer part is diseased, that portion of the same nerve behind the 
decussation presents marks of disease. 

§ 1879. The two optic nerves separate on leaving the decussation, 
and pass through the optic foramina into the cavity of the orbits. Here 
they are situated between the recti muscles of the eye, curve and be- 
come convex outward. When near the eye they contract very much, 
pass through the sclerotica and also the choroid membrane, and termi- 
nate in the organ, expanding in the retina. 

They are first covered with neurilemma be/ore the decussation. 
This membrane has there more firmness than in the other nerves, and 
penetrates within them, forming distinct sheaths. The optic nerves 
differ from all others, not only because they reunite, but also because 
they are intimately enveloped in all their course by a fibrous sheath, 
which is continuous posteriorly with the periosteum of the orbit and 
dura-mater, anteriorly with the sclerotica. 

(1) El. phys. book xvi. vol. v. p. 7o2. 

(2) Wenzel, p. 115. obs. ii. 



82 DESCRIPTIVE ANATOMV. 



XII. OLFACTORY NERVE. 



§ 1880. The olfactory nerve, ihejirsl pair, the ethmoidal nerve (JV. 
olfactorius, s. par primum, the caruncula of the ancients, who con- 
sidered the optic nerves as the first cerebral pair), is situated on the 
lower face of the hemispheres of the cerebrum, in a groove which is 
there seen, but a few lines from their inner edge. It goes a little ob- 
liquely from without inward, so that the cords of the two sides are 
separated anteriorly only by the crista galli process. In this course it 
advances, on the body of the sphenoid bone and the cribriform plate of 
the ethmoid bone, covered by the pia-mater, which extends like a 
bridge from one edge of the groove in which it is situated, to the other. 
This groove, however, is much deeper than the thickness of the nerve, 
and like all the other anfractuosities of the cerebrum, the pia-mater 
exactly covers its surface in all parts. 

The olfactory nerve arises by three medullary bands or roots, from 
the posterior and inner part of the anterior lobe of the cerebrum, where 
this latter unites to the posterior lobe. The external band is the nar- 
rowest and strongest. Convex posteriorly, concave anteriorly, its 
direction is from behind forward, from without inward, and from above 
downward in the fissure of Sylvins, at the union of the anterior lobe 
with the posterior, proceeds at first almost transversely, then descends 
nearly perpendicularly, and reunites with the internal root some dis- 
tance from the posterior extremity of the lower face of the anterior 
lobe. 

The middle root, the shortest, and which it is generally more correct 
to consider only as the internal portion of the external root, arises from 
the centre of the anterior perforated plate or even directly from this 
plate by some fibres of which the internal are concave inward and the 
external are straight. After proceeding from one to two lines, it unites 
to the external root and gives rise to a common trunk a line and a half 
•large and very broad, the direction of which is oblique from behind for- 
ward and from without inward. 

The internal root is from one to four lines long. It comes from the 
internal posterior extremity of the lower face of the anterior lobe, pro- 
ceeds obliquely from above downward, from behind forward, and 
from within outward, and anastomoses with the common trunk of the 
others. 

All these roots are so imbedded in the gray substance that we per- 
ceive only their internal faces, and we cannot demonstrate them in 
every part without separating them by art. 

Very probably all the gray substance in which they are imbedded 
should be regarded as a portion of the cerebrum which is connected 
with the origin of the olfactory nerve. This portion is oblong. It is 
continuous outward with the union of the anterior and posterior lobes, 
backward with the anterior perforated or cribriform plate, forward at 
its outside and inside with two circumvolutions which bound the fis- 



OF THE NERVOUS SYSTEM. 83 

sure of the olfactory nerve. It is loose at its centre and forms the pos- 
terior wall of this fissure within which it projects. 

The nerve enlarges much from behind forward, so that its anterior 
extremity is two or three times thicker than its origin. 

It is prismatic, the base looks downward, the two lateral faces are 
turned inward and outward, and the upper angle is the most acute. 

In its whole extent it is very evidently formed of gray and of white 
substance disposed in longitudinal fibres which proceed at the side of 
each other and interlace together. Its anterior and enlarged extre- 
mity called the bulb of the olfactory nerve (bulbus n. olfactorii), is that 
part where, proportionally speaking, we find the most of gray sub- 
stance. 

In all the rest of the course of the nerve this substance is particu- 
larly abundant in the inner side. On the outside it is seen near the 
lower face. 

The lower face of the bulb is the only part of the olfactory nerve 
whence filaments arise. These filaments, each of which is surrounded 
by a small prolongation of the dura-mater, pass through the openings 
of the cribriform plate of the ethmoid bone, thus enter in the nasal 
fossa, and are mostly distributed in the mucous membrane which lines 
the septum and the turbinated bones. They are distinguished into 
internal, middle, and external. We shall mention the manner in which 
they are distributed when describing the organ of smell. (1) 



CHAPTER III. 



GANGLIONNARY NERVE. 

§ 1881. The ganglionnary nerve, the nervous system of the gan- 
glions, the great sympathetic nerve, the intercostal, the trisplanchnir. 
nerve (N. gangliosus, s. N. sympatheticus magnus, s. intercostalis 
maximus, s. vertebralis, Lieutaud, s. trisplanchnicus, s. syslema vitas 
antomaticoz vegetativoz, Bichat, Gall),(l) differs so remarkably from all 

(1) The olfactory nerve has been considered as the conductor of the sensations- 
produced by odors. Magrendie, however, refers this function to the fifth pair, which 
sends so many different twigs into the nose. He rests his opinion on the fact, that 
the destruction of the olfactory nerves, and even of the anterior cerebral nerves, is- 
not attended with the loss of smell, which, however, is always the case when the 
two nerves of the fifth pair are divided (Le nerf olfactif est-il I'organe de Vodorat ? 
in the Journ. dephys. experim., vol. iv. p. 69). If this opinion be confirmed, the 
ethmoid nerve does not differ in this respect from the hypoglossal. P. T. 

(2) Consult. 1st. On this nerve in general : C. Berg-en, De nervo intercostal^ 
Erfort, 1731. — A. F. Walter, Programma quo parts intercostalis et vagi corporis- 
humani nervorum et ab utroque latere ejus obviorum anatomen cxhibet, Leipsic, 1 7 33, 
1735. — J. F. Huber, De nervo intercostali, de nervo octavi et noni paris deque acces- 
sorio, Cassel, 1744. — C. C. Schmidel, De nervo intercostali, Erlangen, 1754. — M. 
Girardi, De nervo intercostali, Florence, 1791.— A. Portal, Description du nerf inter - 
coital dans I'homme ; in the Mem. de VInstitut,\o\. iv. Paris, an. xi. p. 151, 209, 



84 DESCRIPTIVE ANATOMY. 

the other nerves and is so opposed to the rest of the nervous system in 
several respects that it would be more proper not to place it in the 
same class with the encephalon, the spinal marrow and their nerves, 
but to consider it as a different but subordinate system. 

§ 1882. This system is formed of numerous ganglions, varying in 
number and size not only in both sides of the same subject but also in 
different individuals, and of nervous twigs, some of which unite these 
ganglions in several different ways, while others are given off to enter 
the organs. It .exists uninterruptedly on the two sides and the ante- 
rior face of the vertebral column, along the neck, chest, and abdomen, 
so that its two halves frequently anastomose on the median line ; 
it extends from the base of the skull to the lower extremity of the 
trunk, and is distributed in the organs of vegetative life. 

The ganglions of this nervous system divide in respect to their situa- 
tion and mode of distribution into two classes which comprise, the first 
the internal or central ganglions, the second the limiting ganglions. 

The central ganglions are principally situated in the abdomen, around 
and above the trunks of the large vessels near the principal organs, 
those which appear most independent in their functions. Several adja- 
cent ganglions are united to each other by larger or shorter filaments, 
and thus form a plexus whence arise some nerves which go 
to the organs, also some filaments which anastomose with other 
similar plexuses. The limiting ganglions are situated on the two 
sides of the vertebral column in succession. They are fewer in the 
neck than in the chest and abdomen, and are generally found in the 
two latter sections of the trunk between each two vertebra. They 
are situated behind the serous membranes of the thoracic and abdomi- 
nal cavities, and anastomose by some longitudinal cords with each 
other and with the central ganglions by some oblong or transverse 
fibres, and with most of the nerves of the centre of the nervous system 



in the Anat. vied., vol. iv. — Bock, Ueber das Ganglicnsystcm ; in Abhandlung uber 
dasfunftc Nervcnpaar, Meissen, 1817. — E. H. Weber, Anatomia comparata ncrvi 
sympathetici, Leipsic, 1817. — J. F. Lobstein, Dc nervi sympathetici humanijabrica, 
usu et morbis, Paris, 1823. — 2d. On its origin .- D. Iwanhoff, Dc origine nervorum, 
intercostalium, Strasbnrg-, 1780. — J. Munniks, Obscrvatio qua 'ad illustrandam 
artem medicam, ostenditur origo nervi intercostalis, ejusquc commcrcium cum aliis 
nervis, ab ejus origine usque ad exitum e calvaria, cum autopsia, turn observatis 
medicis confirmata; in his Observ. var., Groningen, 1805, no. ii. — 3d. On some of iti 
parts : C. T. Ludwig-, Dc plexibus nervorum abdominalium atque nervo intercostali 
duplici observationes nonnulLcc, Leipsic, 1772. — H. A. Wrisberg, Obs. anat. de nervi* 
viscerum abdominalium par tic. I; de ganglio plexuque semilunari, Gottingen, 1780. 
G. Walter, Tabulas nervorum thoracis ct abdominis, Berlin, 1783. — H. A. Wrisberg, 
De nervis vise, abdom., part ii., de nervis systematic caliaci. Sectio I ; de nervis gas- 
tricis, qua. est observationum de ganglio plexuque semilunari continuatio ; in the 
Sylloge comment., 1800, p. 551, 570. — H. A. Wrisberg-, Obs. anat. neurolog. de nervis 
viscer. abdom., part iii., de nervis systcmatis cazliaci II ; de nervis hepaticis et sple- 
nicis, qum est observationum de ganglio plexuque semilunari continuatio II, Got- 
tinsren, 1808.— 4th. On its functions. Broussais, Reflexions sur lesfonctions du syi- 
teme nerveux en general, sur celles du grand sympathique en particulier, et sw 
$uelque3 autres points de physiologic ; in the Journ. univ. des sc. mid., vol. xii. 



OF THE NERVOUS SYSTEM. 85 

particularly with the anterior and posterior branches of all the spinal 
nerves by intermediate filaments. 

Such is the most general view of the ganglionnary nerve which can 
be presented. The chain of the limiting ganglions and of the nervous 
cords which unite them have been generally and until lately consi- 
dered as its trunk and its upper extremity as its origin, admitting that 
prolongations proceed outward from these two points to the nervous 
system of animal life, inward to the thoracic and abdominal viscera. 
But now it is admitted to be more proper to describe first its most 
internal part, and to conclude with the history of the ganglions 
which connect it with the nervous system of animal life, and the fila- 
ments which establish this communication. 



I. CENTRAL PORTION. 

§ 1883. The centre of the ganglionnary nerve is formed of several 
ganglionnary plexuses situated in the cavity of the abdomen, and of 
the nerves which proceed from them to the organs, and the limiting 
ganglions. These plexuses considered from above downward are as 
follow : 

§ 1884. The solar plexus, the semilunar ganglion, the suprarenal 
ganglion and median plexus (P. Solaris, Willis, s. G., s. P. semi-litr 
naris, abdominalis, transversus, communis, cerebrum abdominale) de- 
serves to be first studied, since from its size, the constancy of its gan- 
glions whence all the abdominal plexuses emanate, and its direct 
connection with several of the limiting ganglions, it is the real centre 
of the nerve. 

It is situated before the abdominal aorta behind the peritoneum be- 
tween the two renal capsules, and it surrounds the trunk of the coeliac 
arter}'. 

The ganglions which unite to form it vary in number and size. 
We however always find at least two ganglions, a right and a left, 
which when many exist are always the largest. They are almost 
semicircular, generally more than an inch long, about half an inch 
broad in several parts particularly in the centre, and several lines thick 
from before backward. Their convex edge is turned outward, their 
concave edge inward. 

The right is generally much larger than the left, broader in propor- 
tion to its length, angular and rhomboidal. It is situated between 
the ascending vena-cava and the right pillar of the diaphhragm, and 
the right renal artery and the upper extremity of the right renal cap- 
sule. 

The left, smaller, is proportionally larger and more semicircular ; it 
is situated between the left pillar of the diaphragm, the pancreas, the 
splenic artery, and the left renal capsule. 

Both are united by numerous nervous filaments which proceed trans- 
versely from the internal edsre and the two extremities of one to the 

Vol. III. 12 



86 DESCRIPTIVE ANATOMr 

corresponding points of the other. All or most of these filaments ra- 
mify more or less in their course and frequently anastomose. 

We usually observe between the two principal ganglions, particu- 
larly between their lower extremities in the space between the cceliac 
and superior mesenteric arteries, two or three which are smaller : these 
anastomose with each other and with the two larger ones by interme- 
diate filaments, and apparently belong sometimes to the right and 
sometimes to the left ganglion. 

Sometimes the principal ganglions instead of being thicker and 
broader at their centre as is usual, are very narrow there, while they 
enlarge at their extremities. This arrangement is the first step to- 
wards a rare anomaly, where they divide from above downward in a 
variable number of enlargements which communicate by nervous fila- 
ments. The middle enlargements thus formed are generally the 
largest ; but sometimes although more rarely they are smaller than 
the supeiior and inferior, which renders the arrangement of the nerve 
still more abnormal. 

The ganglions in the first case are nearer each other than in this 
latter ; in the latter case they are sometimes united in several nervous 
filaments interwoven like a plexus. Sometimes from three to eleven 
small subordinate ganglions form on the outside above and below one 
or both of the principal ganglions ; from these arise filaments which 
go to the adjacent plexuses, and also those which assist to form the 
great splanchnic nerve. The principal ganglion of the same side is 
more or less enlarged, so that this formation leads still more directly 
to that where it is entirely divided into a considerable number of 
smaller ganglions which are nearly equal in size. 

Of all these forms those where the central portion is most concen- 
trated is evidently superior to the others : they present a very remark- 
able repetition of the development of the centre of the nervous system 
of animal life both in the fetus and in the whole series of animals. 

The whole solar plexus is considerably large and extends longitu- 
dinally from the upper edge of the cceliac artery to below the renat 
arteries, and it is from one to two inches broad. 

It generally divides like the cceliac artery into three principal parts. 

Some nervous filaments proceed directly from its middle and upper 
part ; they unite to other filaments of the left pneumo-gastric nerve r 
give rise to the superior coronary plexus of the stomach, stomo-gas- 
trique, Ch. (P. coronarius, s. ventriculi superior, s. minor), which 
accompanies the superior coronary artery along the small curve of the 
stomach, extends to the left orifice of this viscus and anastomoses par- 
ticularly on the posterior face of the stomach with the inferior coronary 
and the left hepatic plexus, with which it communicates by twigs. 

The second and largest of these plexuses is termed the hepatic 
plexus (P. hepaticus). It descends from left to right. One portion 
attends the right inferior coronary artery along the great curve of the 
stomach, where it is distributed and is termed the inferior coronary 
plexus (P. coronarius stomachicus inferior): the other is larger and 



OF THE NERVOUS SYSTEM. 87 

joins the hepatic vessels with which it goes to the liver. It first at- 
tends the hepatic artery, but near the sinus of the vena-porta it divides 
into a right and a left hepatic plexus. The first is larger than the 
other, and is formed of from six to eight filaments. It enters into the 
right lobe of the liver and the left goes to its left lobe. Both anasto- 
mose with some filaments of the right pneumo-gastric nerve and also 
form at intervals small prominences in the substance of the liver. Be- 
fore entering this gland they send some filaments to the pylorus, and 
also to theduodenal and pancreatic arteries. 

Independent of these plexuses a smaller one is sometimes detached 
from the right semilunar ganglion, the filaments of which proceed 
from behind forward and from below upward in the small lobe of the 
liver. 

The splenic plexus (P. splenicus) arises from the right lower part of 
the solar plexus and the left semilunar ganglion, the branches of which 
accompanying those of the splenic artery which they surround pass 
on the pancreas, send some filaments to this gland, and also to the 
large cul-de-sac of the stomach, where they form the small inferior 
plexus of the stomach (P. ventriculi inferior et minor), and then enter 
into the substance of the spleen with the branches of the splenic ar- 
tery. 

Some branches arise from the lower part of the semilunar ganglions 
of the solar, the hepatic and splenic plexuses, and unite to form the su- 
perior mesenteric plexus (P. mesentericus superior). This plexus ac- 
companies the trunk and branches of the superior mesenteric artery : 
its filaments are distributed principally to the small and large intestine, 
and some enter the pancreas. 

The upper part of the semilunar ganglions sends off on each side 
four or five considerable branches which are enlarged by some filaments 
from the superior mesenteric plexus, descend towards the renal arte- 
ries, and interlacing by five or six subordinate ganglions form the renal 
plexus (P. renalis) on each side, which give numerous ramifications to 
the renal capsules and to the kidneys. 

This plexus communicates upward and outward with the inferior 
thoracic and the superior lumbar ganglions by twigs, of which the 
upper unite in larger branches which go separately to the limiting 
ganglions and the nervous cords by which these latter are united. 

The same plexus is continuous below with the spermatic plexus (P. 
spermaticus), which descends along the spermatic vessels, anastomoses 
with the superior and inferior mesenteric plexuses, gives some fila- 
ments to the ureter, and extends in man to the testicle, in the female 
to the ovary. 

Some branches arise below from the superior mesenteric plexus, 
descend before the abdominal aorta, and enter the inferior mesenteric, 
the left colic plexus (P. mesentericus, s. mesaraicus inferior, s. medius, 
Vieussens). This latter, which is smaller than the upper, embraces 
the inferior mesenteric artery. It contains but a few small ganglions 
near this artery. 



88 DE9CRIFTIVE ANATOMY. 

On entering the pelvis it divides into two pairs, one the proper infr- 
rior mesenteric plexus attends the branches and twigs of the inferior 
mesenteric artery, and anastomoses with the lumbar ganglion and 
sometimes also with the anterior branches of some lumbar nerves. 

The other has a direction outward and downward, is termed the 
hypogastric plexus (P. hypogastrics, s. mesentericus inferior, s. ter- 
tius, s. posterior), anastomoses with the lumbar and sacral portions of 
the terminal cord of the ganglionnary nerve like the sacral nerves, and 
attending the hypogastric vessels is distributed to the rectum and the 
bladder, and in the male to the prostate gland and vesicuke seminaks, 
in the female to the uterus and vagina. It also emerges from the 
pelvis with the external branches of the hypogastric artery. 

II. LIMITING CORD AND ITS BRANCHES. 

§ 1885. We have already mentioned generally the arrangement of 
the limiting cord which is situated on the two sides of the vertebral 
column and the skull. We describe it from above downward, and 
commence by the superior cervical ganglion which exists constantly. 

A. SUPERIOR CERVICAL GANGLION. 

§ 1886. The superior cervical, the olivary ox fusiform ganglion (G. 
cervicale supremum, s. olivare, s. fusiforme), one of the largest of those 
of the ganglionnary nerve, is situated above and behind the angle of 
the lower jaw, behind the internal carotid artery before the transverse 
processes of the second and third cervical vertebrae and the rectus ca- 
pitis major anticus muscle, on the inside of the pneumo-gastric and 
hypoglossal nerves. It is surrounded by a cellular sheath which en- 
velops also the trunk of the pneumo-gastric nerve. 

Its form and size vary much. It is almost always oblong, thinner 
below than above, terminates however also in a point at its upper and 
fusiform extremity. Sometimes it tends to divide into several gan- 
glions situated successively from above downward. The first degree 
of this anomaly is a contraction in its centre. Next comes the 
formation of an upper or lower appendage ; we then observe contrac- 
tions in two or three points.(l) It does not constantly extend en- 
tirely to the carotid canal. Below it usually descends to the third, 
sometimes however to the sixth cervical vertebra. Generally it is an 
inch and a half long and its greatest breadth is three lines ; its length 
however varies from some lines to four inches, but its breadth and 
thickness are always inversely as its length. 

It sends off numerous branches upward, outward, inward, forward, 
and downward. 

(1) Lobstein has figured (tab. v. fig. 3) a superior cervical ganglion which he has 
found double. 



OF THE NERVOUS SYSTEM. 



I. UPPER BRANCHES. 



89 



1 . The superior branch is sometimes although very rarely double, 
leaves the upper extremity of the ganglion, enters into the carotid 
canal, and establishes a communication between the ganglionnary 
nerve and the portion of the nervous system of animal life contained in 
the skull. It is situated behind the internal carotid artery towards the 
lower curve of which it usually divides into two nearly equal branches 
which separate at an acute angle and ascend in the canal before the 
carotid artery, one being more external than the other. 

Opinions vary both in regard to their mode of anastomosis and the 
number of the portions of the nervous system contained within the 
skull, with which the ganglionnary nerve communicates by these 
filaments ; these differences in opinion depend partly on the difficulty 
of dissecting such delicate parts, partly on the varieties in their ar- 
rangement. 

The most ancient opinion was that the ganglionnary nerve anasto- 
mosed only with the fifth pair.(l) 

At a later period it was asserted to anastomose only with the ex- 
ternal motor nerve. (2) 

Then it was admitted to be connected with both. (3) 

Anatomists vary also as to the point where the ganglionnary nerve 
communicates with the two encephalic nerves ; the differences in 
opinions are but slight and trivial in regard to the external motor nerve ; 
but they are great in regard to the fifth pair, for it anastomoses ac- 
cording to some with the trunk of this nerve, (4) according to others 
with one(5) or more(6) or even with all of its branches. Some think 
they communicate directly,(7) others indirectly and by ganglions: (8) 
the descriptions also of the anastomosis with the sixth pair vary in this 
last respect. 

§ 1887. The ganglionnary nerve always anastomoses with the sixth 
pair in the carotid canal by a considerable branch coming from the 
superior cervical ganglion, which ascends along the internal carotid 
artery first on the outside and then on its anterior face. 

(4) Galen, De nervorum originc ; in Op. ornn., Venice, Vol. ii. p. 54. — The Ara- 
bians and the first Italian anatomists have adopted his opinion. Rau and Valsalva 
assert that they have sometimes observed this arrangement since. (Mor"-ao-ni 
Ep. an. xvi. p. 330.) ° b 

(2) Eustachius, tab. xviii. fig. 2.— Morgagni, Adv. anat., vol. vi.p. 30.— Saatorini, 
Obs. anat., c. iii., p. 67. 

(3) Meckel. 

(4) Schmidcl, Munniks, Bock. 

(5) Most authors. 

(6) Laumonier. 

(7) Most authors who have written on this subject, and on neurology in general. 

(8) Petit, loc. cit.— Schmidel, loc. cit.— Laumonier, in Baeher, Journ. dc mid., vol, 
xciii., March, 1793, p. 259.— Munniks, Obs. rar.-Cloquct, Tr. d'anaC, vol. ii., p. 
686. 



90 DESCRIPTIVE ANATOMY 

This branch generally unites to the external motor nerve by a single 
twig which meets it and is detached at an acute angle from the ex- 
ternal and inferior part of the sixth pair during its passage through the 
cavernous sinus. 

This twig is not unfrequently double and sometimes the recurrent 
filament of the external motor nerve bifurcates soon after arising. 

Sometimes also the anastomosing branch of the ganglionnary nerve 
within the sixth pair is double, in which case one proceeds on the out- 
side the other on the inside of the internal carotid artery. 

We frequently and even perhaps always find at the upper part of the 
carotid canal or in the cavernous sinus, instead of a direct anastomosis, 
a ganglion situated on the outside of the internal carotid artery called 
the cavernous ganglion (G. cavernosum). Three or more filaments 
proceed from the summit of this ganglion to the nerve of the sixth 
pair.(l) 

The anastomosis with the trifacial nerve is always by a filament 
which goes to the recurrent twig of the second branch of the fifth pair 
or the vidian nerve. This filament is distributed partly in the carotid 
artery, partly also emerges from the carotid canal, passes through the 
dura-mater and enters the pterygoid canal where it unites with the 
recurrent twig. 

Thus the branch from the upper extremity of the upper cervical 
ganglion usually divides into these two filaments, one of which goes 
to the external motor, the other to the trifacial nerve. 

This bifurcation generally takes place within the carotid canal, sel- 
dom below and never above it. 

Sometimes but rarely also the upper extremity of the superior cer- 
vical ganglion gives origin to two superior branches, which go one to 
the external motor the other to the vidian nerve. 

When this arrangement exists the two anastomotic filaments and 
the vidian nerve communicate with the external motor nerve. Some- 
times also this triple anastomosis does not exist. 

An analogous case is where either the anastomosing filament which 
goes to the external motor nerve or that which proceeds to the trifacial 
or both divide into several filaments, all of which unite in a common 
trunk to go to the superior cervical ganglion. 

§ 1888. This is the only anastomosis admitted by most authors 
between the ganglionnary and the trifacial nerves. In fact it is often 
the only one which can be demonstrated. But the great sympathetic 
nerve also unites by its upper extremity in another manner, at least 
sometimes, with the trifacial nerve. 

Many anatomists, and Portal among others, positively reject this 
other anastomosis ; but many observations favor its existence. 

In fact according to Schmidel and Munniks, several filaments come 
from the ganglionnary plexus of the fifth pair and go to the carotid 

(1) Laumonier, loc. cit. — Munniks, loc. cit. 



OF THE NERVOUS SYSTEM. 



91 



canal, where they unite with other filaments of the external motor 
nerve and form a ganglion. 

Others however whose opinions are like the preceding, assert that 
beside those filaments mentioned, or even if they do not exist, we find 
a smaller twig coming from the first branch of the fifth pair ; and this 
unites sooner or later either with the anastomosing filament of the 
sixth pair, as Petit,(l) Schmidel,(2) and Coopmanns(3) assert, or with 
the cavernous ganglion. (4) 

Laumonier, on the contrary, has found coming from the cavernous 
ganglion, the two filaments which anastomose with the sixth pair and 
the vidian nerve, and also a third which went to the second branch of 
the fifth pair, and a fourth to the fourth branch of this same pair.(5) 
Bock(6) asserts that ten filaments go to the anterior extremity of the 
trunk of the fifth pair, particularly towards the portion which corres- 
ponds to the first branch. 

All these assertions, however agree, in this, that besides the fila- 
ment which anastomoses with the vidian nerve, one or more anasto- 
moses exist nearer the origin of the fifth pair with one or several of its 
three principal branches, or with its trunk : these anastomoses take 
place by a ganglion, and from this arises the filament of communica- 
tion with the superior cervical ganglion. (7) 

We also sometimes find a more indirect anastomosis between the 
upper extremity of the ganglionnary nerve and the third pair of cere- 
bral nerves, the latter anastomosing with the sixth and fifth in the 
place where they give filaments, which communicate with the great 
sympathetic nerve. (8) 

According to Fontana(9) and Ribes,(10) whose correctness we have 
partially attested, the ganglionnary nerve penetrates still farther up- 
ward and forward, for it sends some filaments from the carotid canal to 
the pituitary gland,(l 1) or to theinfundibulum,(12) and also a fasciculus 
which accompanies the ophthalmic artery, forms a plexus around the 
different branches of this vessel, not excepting the central artery of the 
retina, and anastomoses by a filament with the lenticular ganglion, 



(1) Loc. cit., p. 4. 

(2) Loc. cit., p. 16, 2L 

(3) Loc. cit., p. 219. 

(4) Cloquct, loc. cit., p. 687. 

(5) Iac. cit., p. 259. 

(6) Vomfiiiiften Nerven, p. 3. 

(7) Lobstcin does not admit all these anastomoses ; he has seen some transparent 
and gelatinous filaments which united the ramifications of the great sympathetic 
nerve with the common motor and other nerves; but by examining them with the 
microscope, he has not found in them the characters of nervous organs. He regards 
them as cellular tissue extended in filaments. F. T. 

(8) Munniks, loc. cit., p. 25. 

(9) In Girardi, loc. cit., p. 25. As Carus (Anatomie und Physiologie des Nerven- 
systems, p. 185) has also observed in several reptiles. 

(10) Ribes, Rech. anat. etphys. sur quelques parties de Vail: in the Mem. de la soc. 
mea. d'cmiu., vol. vii. p. 97. 

(11) Fontana, loc. cit., p. '56, 57. 

(12) Cloquet, loc. cit. 



92 DESCRIPTIVE ANATOMY. 

consequently with the first principal branch of the fifth, and with the 
third pair.(l). And likewise as there exists also between the lenti- 
cular ganglion, the cavernous sinus, and all the ganglionnary system, 
a constant relation, (2) similar to that between the two ganglions, we 
consider this small filament with the ciliaiy nerves which come from it, 
as making part of the great sympathetic nerve, which supposition 
seems to us very probable. 

II. EXTERNAL BRANCHES. 

The external branches are from one to four in number, pass above 
the rectus capitis major anticus muscle, to go and meet the first and 
second cervical nerve. When there is only one, it is larger, and soon 
divides into as many branches as generally exist, comes sometimes 
from the upper, and sometimes from the centre of the superior cervical 
ganglion. The upper two arise from the upper extremity of this same 
ganglion, directly at the side of each other, and anastomose with the 
anastomotic plexus of the first and second cervical nerves. The third 
communicates with that of the third and fourth cervical pairs. The 
fourth which arises more frequently from the twig of communication 
between the first and second cervical ganglions, anastomoses on one 
side by several filaments with the anastomotic plexus of the third and 
fourth cervical nerves, and is distributed in the rectus capitis major 
anticus and the scalenus anticus muscle. 



III. INTERNAL BRANCHE9. 

The internal branches are much smaller and less constant in respect 
to number, and are distributed to the longus colli, the rectus capitis 
major anticus muscle, the pharynx and the larynx. 

IV. ANTERIOR BRANCHES. 

The anterior branches are the largest and most numerous. They 
are distinguished by their reddish tint and their softness, and hence 
are termed soft nerves (N. molles). The superior are shorter than the 
others, proceed from below upward, and anastomose with the hypo- 
glossal, the pneumo- gastric, and the facial nerves, just after they 
emerge from the skull. The middle and inferior are larger, go forward 
and downward, envelop the primitive carotid arteries to their origin, 
anastomose in this course with some branches of the pneumo-gastric 
nerve, and surround also, together with the facial and pneumo-gastric 
nerves, the branches of the external and internal carotid arteries, to 
the carotid canal. The latter not unfrequently come from a distinct 



small ganglion. 



(1) Ribes.— Cloquct— Bock. 

(2) Ribes. — Cloquet. — Bock. 



OF THE NERVOUS SYSTEM. 93 

The largest anterior branch is the superior or superficial cardiac 
nerve (A*, cardiacus superior, s. superficial), which arises by from 
four to six filaments from the internal anterior part of the cervical gan- 
glion, sometimes also partially or wholly from the upper extremity 
of the cord which joins this ganglion to the following. The minute 
nerve formed by the union of these filaments, descends on the outside 
of the primitive carotid artery, covered by the cord of communication 
of the great sympathetic nerve, gives off at about its centre some fila- 
ments which surround the inferior thyroid artery, anastomoses with 
one or two twigs of the pneumo-gastric nerve, communicates also with 
the descending branch of the hypoglossal nerve, gives ramifications to 
the pharynx, the esophagus, the sterno-hyoideus and sterno-thyroideus 
muscles, and usually terminates partly by anastomosing with some 
ramuscules of the recurrent branch of the pneumo-gastric nerve, and 
partly sends retrograde filaments to the thyroid gland. It more rarely 
descends to the arch of the aorta, where it unites to the middle car- 
diac nerve ; but it never extends to the heart, so that it does not de- 
serve the term applied to it. 

That of the left side commonly extends farther than that of the 
right. 

V. INFERIOR BRANCH. 

The inferior branch establishes the communication between the su- 
perior and the middle, or the inferior cervical ganglion, and is generally 
considered as the continuation of the trunk. It varies in size and firm- 
ness. It is generally thinnest in its centre, and is always larger than the 
superior cardiac nerve which is situated before and on the inside of it. 
It constantly arises from the lower extremity of the superior cervical 
ganglion, with which it is less directly continuous, the larger it is and 
the smaller the ganglion. Its length depends on that of the superior 
ganglion, and on the presence or absence of the middle one. It 
always exists. It is situated before the rectus capitis major amicus 
and the longus colli muscles, near the inner edge of this latter, first be- 
hind the internal carotid artery, then behind the primitive carotid, 
between the internal jugular vein and the pneumo-gastric nerve. 

It is most generally single. Very rarely it is divided at its lower 
part into two twigs, which embrace the inferior thyroid artery, and 
which usually enter, one the middle cervical ganglion, the other the 
inferior cervical ganglion. 

This branch anastomoses by some external filaments with the ac- 
cessory and several cervical nerves, more frequently with the superior 
than the inferior, sometimes even with the eighth. These differences 
and those in the length of the cord, depend on those in the size of the 
superior cervical ganglion, and also on the presence or absence of the 
middle ganglion. The anastomosing branches generally unite in 
some larger branches before coming to the trunk of the ganglionnary 
nerve. 

Vol. III. 13 



94 DESCRIPTIVE ANATOMY. 

From this branch arise some filaments which contribute to form the 
superficial cardiac nerves. It gives some also which unite to others 
coming from the superior cervical ganglion, sometimes arise only from 
the superficial cardiac nerves, and go almost transversely inward, and 
are distributed, the superior particularly, in the constrictor muscles of 
the pharynx, the inferior in the thyroid gland, the muscles, and the 
mucous membrane of the larynx. These filaments frequently anas- 
tomose with each other or with some ramifications of the pneumo- 
gastric and glosso-pharyngeal nerve. 

B. MIDDLE CERVICAL GANGLION. 

1889. The middle cervical or thyroid ganglion (G. cervicale me- 
dium, s. thyroideum) is situated at the origin of the inferior thyroid 
artery, between the fifth and sixth, or between the sixth and seventh 
cervical vertebrae, directly before the longus colli muscle, behind the 
primitive carotid artery and the pneumo-gastric nerve. It is not so 
constant as the superior; it however exists more frequently than it is 
absent, and in the proportion of 3 : 1, judging from our dissections ; it is 
sometimes extremely small, and sometimes deficient. It is never ob- 
long, but always broad and slightly flat. When deficient, we some- 
times, but not always, find in its place two inferior cervical ganglions, 
in which case consequently, it is only situated lower than usual. 
Sometimes, but much more rarely, it is double, that is, it is divided into 
two small ganglions, a superior and an inferior, the former of which is 
then situated higher than the common single ganglion. 

Its branches go upward, outward, inward, forward, and down- 
ward. 

The superior unites it to the superior cervical ganglion, which we 
have already described. 

The external are sometimes reduced in number to one, anastomose 
with one or more of the inferior cervical pairs, especially from the fourth 
to the sixth. 

The internal accompany the inferior thyroid artery, on which they 
give rise to the thyroid plexus (PI. thyroideus), extend to the thyroid 
gland, and go to join and enlarge the recurrent laryngoeal nerve. 

The anterior form the middle or deep cardiac nerve, the great car- 
diac nerve (N. cardiacus medius, s. magnus, s. profundus), which is 
the largest. Five or six filaments unite near the ganglion, first into 
two or three fasciculi, then in a trunk which descends obliquely from 
without inward, first along the primitive carotid artery, then before the 
subclavian, anastomoses in its course by several filaments with the 
trunk of the pneumo-gastric nerve, and with its recurrent branch, and 
unites with the inferior cardiac nerve to form the cardiac plexus. 

The middle cardiac nerve differs on the right and left sides. 

That of the right side, after passing before the subclavian artery, 
descends along the trunk of the innominata, unites at its bifurcation by 
a small ganglion with one or two twigs of the pneumo-gastric nerve, 



OP THE NERVOUS SYSTEM. 95 

and then passes between the arch of the aorta and the bifurcation of 
the trachea. 

That of the left side arises by several filaments from the middle cervi- 
cal ganglion, and from the inferior ganglion by one or two filaments which 
are larger than the preceding. The two ganglions then unite in this 
place, while on the right side they remain separate. The two roots 
unite some distance from the origin of the subclavian artery. The 
trunk passes behind the arch of the aorta, there unites to some fila- 
ments of the pneumo-gastric nerve, and anastomoses with that of the 
right side, and likewise with the two inferior cardiac nerves, to form 
the cardiac plexus. 

The inferior branches are very minute, shorter than the rest, and 
five or six in number. They descend on the right side before and 
behind the subclavian artery, on the left side before and behind the 
trunk of the aorta, and anastomose with the superior ascending 
branches of the inferior cervical ganglion. 

Sometimes the anterior of these branches are deficient, and the pos- 
terior also are united in a short common trunk, which establishes a 
direct connection between the two cervical ganglions. 

C. INFERIOR CERVICAL GANGLION. 

§ 1890. The inferior cervical ganglion (G. cervicale inferius) is 
much more constant than the central, and is generally flat, rarely 
rounded and oblong, often very irregular, and sometimes double. It 
is situated before the transverse process of the seventh cervical vertebra 
and the neck of the first rib, but sometimes descends to the second 
rib. 

Its superior branches anastomose with the inferior of the middle 
ganglion. One which is rather large, enters the vertebral canal, 
where it entwines around the vertebral artery, sends some filaments to 
the intertransversarii muscles, and terminates at the third or second 
cervical vertebra. 

Sometimes this branch arises only from the filaments which anasto- 
mose with the brachial plexus. 

The external are smaller, but numerous, surround the subclavian 
artery, and give ramifications to the muscles of the neck, and anas- 
tomose with the two or three inferior cervical nerves, and also with 
the first dorsal, sometimes even but more rarely with the second tho- 
racic pair, when the inferior cervical ganglion is much developed. 

The internal terminate principally in the longus colli muscle and 
the pulmonary plexus. 

The anterior form the inferior cardiac nerve ( JV. cardiacus inferior. 
s. tertius } s. parvus), which generally exists only on the right side, while 
on the left it is only indicated by the inferior root of the great cardiac 
nerve. These branches frequently interlace before uniting in a single 
trunk. The latter descends first behind the subclavian artery, then 
before the innominata and the arch of the aorta, anastomoses often 



96 DESCRIPTIVE ANATOMY. 

with the pneumogastric nerve, gives some filaments to the vessels 
situated near its course, and goes to the left between the aorta and the 
pulmonary artery, and terminates in the anterior cardiac plexus. 



CABDIAC PLEXUS. 



§ 1891. The cardiac plexus (PI. cardiacus) is formed principally by 
the middle cardiac nerves. It is situated between the arch of the 
aoita and the bifurcation of the trachea. It extends from the division 
of the pulmonary artery to the origin of the innominata. 

Its anterior filaments go principally to the anterior wall of the aorta, 
and the posterior to the pulmonary plexus. The inferior are more 
numerous, and go almost exclusively to the heart, where they form 
the two coronary plexuses (PI. coronarii), in which also terminate 
some filaments of the inferior, and more generally of the superior 
cardiac nerve. 

The posterior coronary plexus is much larger than the anterior ; it 
goes to the base of the heart, descending on the left pulmonary artery. 
It is distributed to the lower and posterior part of the left ventricle 
along the posterior coronary artery and its branches. 

The anterior follows the course of the left inferior cardiac nerve, in 
its whole extent, passes between the aorta and the pulmonary artery 
and after anastomosing at its upper part with the posterior, attends 
the anterior coronary artery and its ramifications, on the upper face of 
the heart and the right auricle, where it frequently anastomoses with 
the posterior, along the posterior edge of the organ. Some smaller 
twigs of this plexus proceed on the left pulmonary artery, and go to 
the pulmonary plexus of the left side. 

The two plexuses frequently anastomose with some branches of the 
pneumo-gastric nerve. 

They are, however, mostly formed by the ganglionnary nerve. 

After leaving the lower part of the neck, the ganglions of the great 
sympathetic nerve are more numerous. 

D. THORACIC GANGLIONS. . 

§ 1892. We find in the chest between the transverse processes of 
each two vertebrae, and on each side, a ganglion called the thoracic 
(Gl. thoracicum). These ganglions are generally slightly rounded, 
elongated, triangular, and- fusiform. They are situated more on the 
outside than the cervical. The first counting from above downward 
(G. thoracicum supremum) is the largest of all the limiting ganglions 
except the superior cervical. Sometimes it is blended with the second • 
this, however, is rare, and even when it appears, generally exists on 
the outside. The middle ganglions are often a little smaller than the 
superior and the inferior. 



OF THE NERVOUS SYSTEM. 97 

All these ganglions are united to each other by one very strong 
filament, rarely by two. 

The superior is almost constantly attached to the inferior cervical 
nerve by two filaments, the anterior, of which not unfrequently divides 
in turn into two smaller filaments. Each thoracic ganglion anastomoses 
on the outside by two filaments, with its corresponding thoracic nerve. 
Internally, the superior gives off branches, some of which go to the 
lower part of the longus colli muscle, others to the cardiac plexus, 
several to the pulmonary plexus, which, however, is principally formed 
by the pneumo-gastric nerve ; finally, some proceed to the aorta. 

I. SPLANCHNIC NERVE. 

§ 1893. From the inferior thoracic ganglions, and from their fila- 
ments of union, generally from the sixth or the seventh to the eleventh, 
arise cords, the upper of which are usually the largest ; they vary in 
number from three to seven, and are very rarely the same on both 
sides of the body ; they unite at an acute angle near the diaphragm, 
to form the splanchnic nerve, grand surrenal, Ch. (JV. splanchnicus). 
This nerve descends behind the pleura, and generally goes from the 
chest into the abdomen, between the inner and middle prolongations 
of the pillar of the diaphragm, sometimes also through the aortic open- 
ing. It anastomoses in the abdomen principally with the semilunar 
ganglion of its side, sometimes directly, sometimes indirectly, by some 
small ganglions. It then forms the principle mode of union between 
the central portion of the ganglionnary nerve and the limiting gan- 
glions. Not unfrequently some of the roots by which it arises, parti- 
cularly the inferior, go separately to the semilunar ganglion, and some 
of them often anastomose, not with this ganglion, but with some fila- 
ments of the solar, the hepatic, the splenic, and the two renal plexuses. 

II. SMALL SPLANCHNIC NEEVE. 

§ 1894. Two or three inferior branches, which, however, remain 
distinct, sometimes unite on the right side more frequently than on the 
left, in a small special trunk, called the small splanchnic nerve, petit 
surrenal, Ch. (JV*. splanchnicus minor.) This trunk passes through 
the pillar of the diaphragm below the preceding. It is enlarged by 
some filaments from the superior lumbar ganglions, and goes princi- 
pally into the renal plexus, which is often in great part formed by it. 

E. ABDOMINAL GANGLIONS. 

§ 1895. The cord by which the limiting ganglions unite is always 
very small below the origin of the splanchnic nerve. Sometimes it is 
entirely deficient in some points, so that the trunk of the great sympa- 



98 DESCRIPTIVE ANATOMY. 

thetic nerve is there interrupted(l) and the limiting ganglions form one 
and the same series with the abdominal ganglions and plexuses only 
by intermediate connections. When this series comes on the lumbar 
vertebrae it goes forward. We there see ganglions which are much 
smaller, more remote from each other, and less constant in their situa- 
tion than those hitherto examined. The upper is always larger than 
the others, which gradually diminish from above downward and often 
do not exist, or at least are almost invisible. 

The upper pelvic ganglions of the limiting cord are a little larger 
than the inferior lumbar, and form a series which converges from above 
downward. There are usually four or five, the lowest of which is 
situated forward between the sacrum and the coccyx, and anastomoses 
with the corresponding ganglion of the opposite side by a shortened 
thin filament which is convex downward. 

The lumbar and pelvic ganglions are united by some filaments 
which differ from those existing between the others in their length and 
also in their number and size ; for there are usually three or four be- 
tween each two ganglions, which are much smaller than those be- 
tween the superior ganglions. 

Their external branches proceed to meet the lumbar and sacral 
nerves, and anastomose with their anterior branches near the inter- 
vertebral and sacral foramina. 

Those of the superior lumbar ganglions have a direction oblique 
from below upward. 

The middle are transverse, and the superior oblique from above 
downward. The latter are very long, the first very short. Some 
which are smaller go upward to the psoas muscle, downward to the 
pyramidalis and to the levator ani muscles. 

The lumbar ganglions give off some internal branches which go to 
the anterior face of the aorta, and contribute to form the aortic plexus 
which comes from the superior mesenteric plexus. Some of the sacral 
ganglions anastomose together before the sacrum ; others terminate 
in the hypogastric plexus. 

The series of limiting ganglions terminates below in some filaments 
which radiate from the last of them, and which are distributed in the 
lower and posterior part of the rectum. 

§ 1896. Our mode of describing the ganglionnary nerve differs from 
that hitherto adopted even by those anatomists who consider it as 
directly opposed to the rest of the system, for they generally commence 
by that part which descends along the vertebral column, by the ex- 
ternal ganglionnary cord, and terminate with the central portion. 

(1) This has been seen twice by Haller (Elem. phys., vol. iv. p. 261). Bichat haa 
also made this remark {Rech. phys. sur la vie et la mort, p. 82), and uses this as the 
principal argument in favor of his opinion, that the sympathetic nerve does not form 
a continuous trunk from the head to the pelvis. Wrisbcrg ( Obs. anat. de ganglia 
plexuque semilunari, § 19, in the Comm. Gcetting, 1779, vol. ii. p. 102) has admitted 
this arrangement to be an anomaly, and Weber (Anat. comp. nervi sympath.. p. 122 
regards this observation as doubtful. 



OP THE NERVOUS SYSTEM. 99 

Our course will at first view be more surprising, because we have 
several times mentioned that there is no manifest contrariety between 
the two nervous systems. 

In fact the ganglionnary nerve is only the highest development of a 
form which has passed through several gradations. We may consider 
the diaphragmatic nerve as the first of these : this arises from several 
cervical pairs, and passes some distance to go to a voluntary muscle, 
the diaphragm, the principal agent in respiration. This formation is 
still more developed in the four posterior cerebral nerves, particularly 
in the pneumo-gastric, which forms plexiform anastomoses with the 
superior cervical nerves, descends along the neck, is distributed to the 
organs of respiration, and descends to the stomach in the abdominal 
cavity. The whole course of this nerve favors our analogies still more, 
inasmuch as it forms numerous plexuses whence branches proceed to 
the organs. 

The ganglionnary nerve, if we except some filaments which arise 
perhaps from the pituitary gland, does not commence directly at the cen- 
tre of the nervous system, but from several of the cerebral and from all 
the spinal nerves. It descends lower than the pneumo-gastric nerves, 
gives some filaments to all those organs of vegetative life which re- 
ceive none from this latter, and frequently anastomoses with the two 
preceding. The plexiform and ganglionnary structure is more evident 
ia it than in any other nerve, so that even the inner part of its expan- 
sion exceeds the outer ; and hence from its form, situation, and con- 
nections with the encephalon and spinal marrow, it may be regarded 
as the trunk of the nerve, as is generally admitted, and thus the inner 
part is considered the central portion. 

These are our reasons for departing from the common course, al- 
though the anatomical and the physiological relations of the gangli- 
onnary nerve prove that it is dependent on the centre of the nervoua 
system, being connected with it -by its outer part. 



CHAPTER IV. 

DIFFERENCES PRESENTED BY THE NERVES DURING THEIF* 
DEVELOPMENT. 

§ 1897. The differences presented by the nerves during their deve- 
lopment have been but slightly studied, and we have but few observa- 
tions which refer to them. Not having had sufficient opportunities of 
obtaining well preserved human fetuses, we cannot add as many re- 
marks as are desirable to those already existing. 

We may state on this subject the following corollaries : 
1st. All the nerves are not developed with equal rapidity in respect 
to color, texture, and consistence. The spinal generally increase 



100 DESCRIPTIVE ANATOMY. 

faster than the cerebral nerves. We have found them perfectly white 
and evidently fibrous in the fetus of six months, while the cerebral 
nerves were gray. The fibrous texture and color are developed latest 
in the optic nerves. At six months it is much larger than the other 
encephalic nerves, and even at the ninth month of pregnancy it is still 
as gray as the rest of the cortical substance, is very soft, and presents 
no appearance of fibres. We have not yet been able to determine if it 
whitens before birth ; it however experiences this change early, for in 
two children one month old we have found it perfectly white in all its 
course, except most of the portion between the decussation and the 
eye ; the latter was entirely white before the decussation, gray on the 
outside and white on the inside in the centre ; finally totally gray for- 
ward. 

We may conclude from these facts that the nerves complete their 
development from within outward and from behind forward. This 
proposition applies both to the different nerves and to the same nerves 
in different parts of the body. It is then very curious that the olfac- 
tory nerve which is the most anterior remains almost entirely gray 
during life, and constantly preserves this tint in its whole anterior part. 
This law seems to be general, for we have since met with it in fetuses 
of the hog and cat. 

We have also found the great root of the trifacial nerve entirely gray 
in the fetus of eight months. 

2d. The following remarks are applicable to the other differences 
presented by the nerves : 

Among the spinal nerves we have found in a great many fetuses 
the crural nerve divided on emerging from the pelvis into its tibial and 
peroneal branches, which were the more distinct the younger the fetus. 

Before the end of the fifth month of pregnancy they were not united 
so intimately as they are at an advanced age ; hence this arrangement, 
which is abnormal in the adult, is normal during the early periods of 
existence.(l) We have not been able as yet to observe any difference 
in the other spinal nerves. 

The trifacial nerve differs from what it is in the adult : 

1. In the number of its cords, which are at first fewer. In the fetus 
of eight months there are only eighteen in the large root, while there 
are from twenty-eight to thirty in a child when born. (2) 

2. The texture of its ganglionnary plexus is less fibrous. We have 
found structure of this plexus was homogeneous at the sixth month 
of pregnancy. 

These two peculiarities may be referred to the same principle, the 
imperfect development of the nervous tissue. 

(1) We have already said that this arrangement is curious as analogous with the 
mammalia, hut did not intend to assert that it is common to all these animals. 

(2) Vesting, Obs. anat., no. viii. — Scemmerring, Dc basi cnccphali. § 60.— Nie- 
meyer, in Reil, Archiv. fur die Physiologic, vol. xi., p. 51 



OF THE NERVOUS SYSTEM. 101 

The olfactory nerve is at first proportionally much larger ; at the 
same time it is rounded, thicker, and shorter. 

Until the sixth month there is within it a cavity which communi- 
cates with the lateral ventricles of the cerebrum. 

These are two remarkable analogies with the mammalia. 

In the full grown fetus its external root is evidently medullary. We 
perceive also some medullary striae on the lower face of the nerve, but 
there is no trace of the medullary band which represents its internal 
root. 

In the early periods of fetal existence the great sympathetic nerve is 
more developed in proportion to the body than almost any other part of 
the nervous system. It is very remarkable that the large limiting gan- 
glions are so near each other, particularly in the chest, that they form 
an uninterrupted series. The splanchnic nerve is also proportionally 
much thicker than in the adult. 

At about the middle of fetal existence this nerve has diminished 
much, and then presents very nearly the proportions which continue 
during life.(l) 



CHAPTER V. 

PARALLEL BETWEEN THE DIFFERENT NERVES* 
I. BETWEEN THE SPINAL AND THE ENCEPHALIC NERVES. 

§ 1898. .The spinal and encephalic nerves are generally strictly 
opposed to each other, and are distinguished by characters mentioned 
previously (§ 170) ; but the differences between them are not so dis- 
tinct as is asserted. First those which truly exist do not prevent us 
from considering the encephalic nerves in the condition of spinal nerves, 
and from demonstrating that they are only modifications of the latter, 
and from investigating the cause of these modifications. 

All the encephalic nerves are portions of spinal nerves which are 
not united in a single trunk like the latter, but are developed as so 
many separate nerves. This modification of the primitive type de- 
pends on the development of the centre of the nervous system within 
the skull and on that of the skull itself, which mechanically separates 
the different groups of the roots of the nerves at their origin and in 
their course. 

It also depends on special organs, those of the senses, which are de- 
veloped in the skull, the roots of which are formed by the nerves that 
go to them, and which are perfect in the direct ratio of the development 
of their special nerves. Comparative anatomy demonstrates, at least 

(1) Lobstein has given a history of the evolution of the ganglionnary nerve in the 
fetus, and the modifications it experiences aa age advances {foe. cit., p. 47-56.) 
Vol. III. 14 



102 DESCRIPTIVE ANATOMT. 

in regard to several organs of the senses, that new nerves are not 
formed for them,(l) but only that single branches arising from a spe- 
cial part of the encephalon become trunks. In fact we see several 
nerves, especially among those of the organs of the senses, which form 
separate trunks in superior animals, are only subordinate branches in 
the inferior animals. This is the case particularly with the trifacial 
nerve ; and this is much more evident the more inferior the animal. 

This development of portions of nerves which raises them to the 
rank of distinct nerves is gradually increased from the posterior to the 
anterior extremity of the cerebrum. It is manifested in the posterior 
pairs only by the want of union between the anterior and posterior 
roots ; but the anterior roots seem to be formed from the fact that single 
fasciculi appear to be the proper nerves. 

The nervous system then follows precisely the same type as the 
other systems, particularly the osseous ; for the bones of the skull are 
more similar to the vertebrae the more posteriorly they are situated, and 
the dissimilarity between them and the vertebrae which gradually in- 
creases from behind forward, depends principally upon the fact that 
simple portions of the vertebrae have become sufficiently developed to 
be considered distinct pieces of bone. 

In this view of the- subject, we should consider the last four cerebral 
pairs, the accessory, the pneumo-gastric, the glosso-pharyngeal, and 
the hypoglossal nerves, as so many sections of one and the same nerve, 
the posterior of which is formed by the first three nerves, and the an- 
terior by the fourth. In fact, the accessory, the pneumo-gastric, and 
the glosso-pharyngeal nerves, arise by an uninterrupted series from the 
posterior cord of the spinal marrow, and emerge from the skull through 
the same opening. They thus form in the skull, trunks;*lhe external 
parts of which are sepaiate from each other, and generally pass 
through the dura-mater in different points. But this is far from being 
the ease with the accessory nerve, and even when it is, the accessory 
is adapted to the pneumo-gastric nerve so intimately, that they form 
a single trunk. Beside, after the two nerves separate, the inner 
branch of the accessory nerve again unites with the eighth pair, and 
continues with it. The glosso-pharyngeal nerve also anastomoses by 
one filament even within the cranium, with the pneumo-gastric nerve, 
and after leaving the skull, they communicate by several other fila- 
ments. It is curious that the accessory and pneumo-gastric nerves 
on one side, the glosso-pharyngeal nerve on the other, and just before 
where it unites with the two preceeding, form ganglions near the 
place where they emerge from the skull, exactly as do the posterior 

(1) See on this subject the important memoir of Treviranus, in which he proves 
that the nerves of the fifth pair take the place of those of very important senses in 
some animals, and that there is in these animals some organs of sense very different 
from those of man, the nerves of which are the branches of the fifth pair (Sur les 
Tierfsde la cinquiimc paire, considcrcs comme organcs ou conducteurs de sensations ; 
in the Journ. oompUm. des sc. vied., vol. xv. p. 207). His observations have been 
confirmed since by Magendie. p_ y 



01 THE NERVOUS SYSTEM. 103 

roots of the spinal nerves ; nor ought we to omit mentioning that the 
posterior root of the superior cervical nerve often joins the accessory, 
which then assumes the character of the posterior root, which cha- 
racter is also expressed very distinctly by its situation behind the liga- 
mentum denticulatum. 

The glosso-pharyngeal nerve, the anterior root of this pair of nerves, 
arises from the anterior cord of the medulla oblongata, like the other 
anterior roots of the spinal nerves, and as its origin is situated more 
inward and forward, it also emerges from the skull through an open- 
ing situated more inward and forward. In fact, it leaves the skull 
through a special opening in the occipital bone, rather distant from 
that through which the other three pass. But this difference from 
the spinal nerves depend on the two causes mentioned above, and we 
see in it only a greater development of the arrangement of the anterior 
and posterior roots of the spinal nerves which pass through distinct 
openings in the dura-mater before uniting ; finally, the glosso-pharyn- 
geal nerve just after leaving the skull, is adapted directly to the trunk of 
the pneumo-gastric nerve, anastomoses with it by some filaments, par- 
ticularly below its ganglion, and goes forward, while the eighth pair, 
united with the other two, is distributed principally below and back- 
ward. We ought not to forget that this nerve never forms the gan- 
glion alcne, and rarely pr never communicates with the ganglion of 
the three posterior nerves. 

The fasciculi of this nerve, like those of the first three, frequently 
emerge from the dura-mater, and sometimes from the skull, through 
distinct openings, but this difference is not essential, for if the fasciculi 
of each of the roots of the spinal nerves unite in man before that each 
root passes through the dura-mater, in the mammalia, they perforate 
this membrane in three or four points, and before uniting, as is also 
true of the nerves of which we speak. Comparative anatomy fur- 
nishes several other facts which prove the parallel stated by us. In 
fishes, the anterior and posterior roots of the spinal nerves emerge 
separately from the spinal column through special openings, so that 
they are still more similar to the cerebral nerves in this class of the 
animal kingdom. On the other hand, in most of the mammalia the 
first cervical nerve, and even the second in some, particularly the hog 
and the ox, frequently arise entirely from the anterior cord of the 
spinal marrow, and form only the anterior root of a spinal nerve, which 
does not emerge through a groove, but through an opening in the 
first and second cervical vertebrae. In almost all the mammalia the 
posterior root of the first cervical nerve enlarges into a ganglion long 
before it unites with the anterior, and before the nerve passes through 
the first cervical vertebra. The ganglion sometimes divides, as we have 
often observed in the hog for instance, into two enlargements, an an- 
terior and a posterior, or at least we not unfrequently observe a deep 
strangulation at its centre and the portion of the posterior root between 
it and the part of the nerve where it emerges from the vertebral 
column, forms two in the hog, an anterior and a posterior ; this shows 



104 DESCRIPTIVE ANATOMT. 

that in this animal, except in the first cervical nerve, the posterior root 
tends to separate from the anterior, and to become a distinct and _ 
special nerve. 

From all these remarks it is not difficult to reduce the last four cere- 
bral pairs. 

Scemmerring had already remarked that the glossopharyngeal nerve 
appeared at its origin like each of the spinal nerves ; hence, it ought 
not to be separated from them and be considered an encephalic 
nerve.(l) The same anatomist compared the origin of the pneumo- 
gastric to that of the spinal ncrves.(2) Finally, others had considered 
the accessory as a spinal nerve, or as* making the transition from the 
spinal to the encephalic nerves. But each admits that these compari- 
sons, founded on peculiarities which escape the eye, have no connec- 
tion with the proposition we establish, viz. that the last four cerebral 
pairs form in fact only one encephalic nerve, the posterior root of which 
emerges through the intervertebral foramen, situated between the 
last and the last but one of the vertebrae of the skull (the occipital 
and the temporal bones), while the second emerges from it only 
through the last cephalic vertebra. 

The reduction of the other eight pairs is more difficult. Some, 
however, the common and the external motor, evidently have the 
characters of anterior roots, or at least of portions of anterior roots j 
others, as the auditory and the superior motor nerve, present no less 
manifestly those of the posterior roots. It is more difficult to determine 
in regard to the rest. We may, nevertheless, compare the facial with 
the auditory nerve, and consequently with the posterior roots, on 
account of its course and the nearness of its origin, even as the origin 
and the course of the trifacial nerve authorize us to arrange it along 
the anterior roots. As to the two anterior pairs, the second may be 
compared to a posterior root, because it arises from the tubercula 
quadrigemina and the optic beds, and the first may be compared to an 
anterior root. We may then consider four pairs as anterior roots, and 
four as posterior roots, or as portions of these roots. It is now easy to 
to refer the auditory, the facial, the trifacial, and the motor nerve, to a 
single trunk. When we follow the origin of the facial, trifacial, and 
auditory nerves within the cerebrum and backward, we see that they 
singularly approach each other. In regard to the facial and the audi- 
tory nerve, we must mention beside the nearness of their origins, the 
remark of Santorini, that we can trace below the transverse fibres of 
the annular protuberance, to the origin of the auditory nerve, some 
fibres which from their progress and direction, arc evidently the com- 
mencement of the facial nerve. (3) The trifacial nerve which partly 
arises from the olivary bodies, blends here with the sixth pair. The 
common motor nerve goes from before backward to meet all these 

(1) De basi cnccphaU ; in Ludwiv, lor. n't., p. 103 

(2) Loc.ciL, p. 101. 

(3) Seplcmdec. tab. p. 23. 



OF THK NERVOUS SYSTEM. 105 

nerves in the annular protuberance. The superior motor nerve and 
the optic nerve, are also very intimately united with them by the band 
which extends from the medulla oblongata to the tubercula quadri- 
gemina. 

The demonstration is most difficult with regard to the two anterior 
nerves ; still the short distance between the origins of the external 
motor and optic nerves, indicate that the latter depends on the others, 
and the anterior commissure unites the olfactory and the optic nerves. 

II. PARALLEL BETWEEN THE NERVES OF THE UPPER AND LOWER EX- 
TREMITIES. 

§ 1899. The nerves of the upper and lower extremities, like the 
bones, the muscles, and the vessels, are formed essentially after the 
same type, and differ only by slight modifications of this type, which 
is subject to the same laws as those of the other three systems. 

At first view the number of the pairs of nerves which unite to form 
the nerves of the two extremities, seem to differ considerably, as there 
are but five pairs of nerves of the upper extremities, while those of the 
lower are formed by ten. This difference, however, vanishes on strict 
examination. In fact, all the cervical nerves are evidently arranged 
among those which concur to form the brachial plexus, since they are 
all united and changed into a real plexus like all the lumbar and 
sacral nerves, by large anastomoses between their anterior branches. 
Further, the difference in number between the nerves of the two ex- 
tremities is only one pair. But we may also explain this apparent 
anomaly by considering the last four encephalic nerves, the glosso- 
pharyngeal, the accessory, the pneumo-gastric, and the hypoglossal 
nerves as one pair, which corresponds to the branches of the inferior 
sacral nerves. This comparison is authorized by the discussion in re- 
gard to the origin of these four nerves which we have mentioned, and 
by considering the manner in which they are distributed. In fact, 
they give off branches to the tongue and upper part of the intestinal 
canal, even as the inferior sacral nerves send them to the organs of 
generation and to the lower part of the intestinal canal. 

All these analogies admitted, the number of pairs of nerves in the 
two extremities is equal : we must not, however, attach much im- 
portance to this uniformity of number, nor consume time in endeavor- 
ing to establish it, for it is unimportant, but presents itself so naturally, 
that it would be wrong to neglect it. 

We may also proceed in an opposite manner, and decompose the su- 
perior and inferior plexuses, considering separately the deep cervical 
and brachial plexuses above, and the lombo-abdominal and sacral 
plexuses below, and oppose them to each other. This is Bichat's 
method. But it is inferior to the other, because it obliges us to 
separate parts which are united. 

The principal common relations between the nerves of the two ex- 
tremities in their distribution, are as follow : 



106 DESCRIPTIVE ANATOMT. 

The superior cervical nerves are distributed to the muscles and in- 
teguments of the neck, the same as the superior lumbar nerves are to 
the muscles and skin of the loins. The first sends some branches to 
the skin of the shoulder, the suprascapular nerves, while the second 
furnish some to the skin of the haunch and the arms. 

The thoracic nerves correspond to the obturator nerve by their high 
origin, their course below the bones of the same part, and their distri- 
bution to muscles which correspond. 

The scapular nerve is the superior gluteal. 

The axillary nerve is the inferior gluteal. 

The nerves which are distributed lower in the two extremities] differ 
much more, since two twigs and even large branches, which corres- 
pond in their mode of distribution, arise from different trunks. The 
branches, however, are the same, and we can easily explain their dif- 
ferences in respect to origin. 

The nerves yet to be compared are in the upper extremity, the internal 
and the external cutaneous nerve, the radial, the median, and the 
ulnar nerve ; in the lower extremity, the crural and the sciatic nerve. 

The external cutaneous radial nerves correspond to the crural : the 
internal cutaneous, the median, and the ulnar nerve, to the sciatic. 

The external cutaneous nerve and the long cutaneous branch of the ra- 
dial nerve, are evidently the superior and inferior internal saphena nerves 
of the lower extremity, since they descend along the side of the thumb 
and of the large toe, which is the internal the the upper limb is in a 
moderate degree of pronation, and is always so in the lower extremity 
when it is at rest. 

The muscular branches of the crural nerve are the upper branches 
of the radial nerve. They are distributed in the extensor muscles of 
the leg, as the latter are in those of the fore- arm. 

The analogy, however, between the radial and crural nerves, ceases 
there. The lower branches given off by the latter are represented in 
the leg, but come there from the sciatic nerve. 

The superior and posterior cutaneous nerves of this latter, very evi- 
dently correspond to the upper branches of the internal cutaneous 
nerve of the arm, since they descend on the outer or fibular side of 
the little toe, as these latter do on the ulnar side of the little finger. 

The tibial nerve corresponds principally to the median and a part of 
■the ulnar nerve. The peroneal represents the lower part of the ulnar 
nerve, and still more that of the radial. We may compare the posterior 
cutaneous branch of the tibial nerve, which so frequently arises from 
the peroneal nerve, to some ramifications of the internal cutaneous 
brachial nerve. 

The muscular branches given by this nerve to the leg correspond to 
those sent by the median nerve to the muscles of the fore-arm. 

The superficial plantar nerve is represented by the superficial palmar 
branch of the median nerve. 

The internal plantar nerve corresponds exactly to the palmar branch 
of the median nerve. 



OF THE NERVOUS SYSTEM. 107 

The external plantar nerve is represented by the palmar branch of 
the ulnar nerve. 

The muscular branch of the peroneal nerve corresponds to the mus- 
cular branches of the radial and ulnar nerves of the fore-arm. 

The cutaneous branch which is distributed in the back of the foot 
corresponds by its external twig to the dorsal branch of the ulnar 
nerve, and by the internal to that of the radial nerve. 

§ 1900. The differences here remarked may be easily explained : 

1st. Some nerves which arise as distinct trunks in the upper extre- 
mity are one nerve in the lower. 

2d. Some branches arise from different trunks. 

These two anomalies depend on the general difference in the form 
of the two extremities. 

1st. As the fibula, from its smallness and its want of articulation with 
the tibia, seems reduced in man to a simple constituent part of the 
tibia ; as several muscles of the leg are attached in a common ten- 
don, while others situated in the fore-arm in the upper extremity are 
found in the sole of the foot ; as the external cutaneous vein of the 
pelvic limb unites with the internal at the knee, while these two veins 
remain distinct to the axilla in the upper extremity ; finally as the arte- 
ries often divide very high in the upper extremity, while this anomaly 
is very rare in the lower, so likewise the nervous trunks which sepa- 
rate very early in the arm, long remain united in the leg. 

Farther, the tibial and peroneal nerves are not only sometimes dis- 
tinct in the pelvis as those of the upper extremity sometimes are in the 
axilla : but also the cutaneous nerves of the arm are frequently simple 
branches of the three larger nerves. The difference mentioned above 
in the crural nerve during its development, also establishes a greater 
analogy between the two limbs in the early periods of life than at a 
more advanced age. 

2d. The difference in origin depends partly on the preceding fact, 
partly also on the difference in the direction and situation of the two. 
extremities. If the arm is in the state of pronation, and thus possesses 
a direction similar to that of the lower extremity, these differences are 
explained with facility. 

The radial nerve is then drawn up as high as the elbow, so that we 
may imagine it to terminate here, and that its lower part unites with 
the ulnar nerve. 

The antibrachial parts of the median and ulnar nerves are also ap- 
proximated, and they blend in a single trunk which divides into tw©> 
branches at the palm of the hand. 



BOOK VI. 



SPLANCHNOLOGY. 



§ 1901. Splanchnology, or the branch of anatomy which treats of 
the apparatus for the functions, includes the description of the most 
complex parts of the organism, those formed by the union of a greater 
or less number of simple organs or systems. We cannot consider these 
as belonging to the class of those already mentioned, as they differ too 
much from these latter or from each other. We must however re- 
mark that they may finally be referred in respect to their essential 
characters to the cutaneous and glandular systems. 

In regard to their functions they may be divided into two classes, 
one of which establishes an immaterial, the other a material connection 
between the organism and the external world. The first are the 
organs of sense, the others are properly termed the viscera. 

The organs of the senses perceive actively the impressions of quali- 
ties belonging to the body which they contribute to form, or to external 
objects. They transmit them to the brain by means of their nerves, 
and cause in this viscus the formation of ideas, that is, they there 
produce modifications of the principle of the mind, of which it is the im- 
mediate organ. 

Some of the viscera receive foreign external substances, others re- 
move all that the vital powers have rendered useless, or separate parts 
proper to form similar new bodies, that is, they remove from the organ- 
ism all that is useless and which cannot serve to preserve the species. 
Some of these organs, as the intestinal canal and the lungs, perform 
both of these functions at the same time ; others, as the kidneys and 
genital organs, serve only for the excretory function ; they all have 
this in common, that they form new substances, and that they thus pre- 
serve the individual in the normal state. The substance formed by the 
genital organs serves also and in a special manner to preserve the 
species. 

However different the results and the mode of action of the organs 
of sense and the apparatus of formation may be, the first are in regard 
to mind exactly the same as are the second in relation to the body. 
Farther the inferior senses, those of smell, taste, and touch, which are 
the bases of all, insensibly establish the transition from the superior 
senses, those of sight and hearing, to the proper viscera, both in respect 
to their form and situation, and to their mode of action. We may also 

Vol. III. 15 



110 DESCRIPTIVE ANATOMr. 

admit that the organs of sense and the viscera have several characters 
in common ; these are : 

1st. They are developments of the cutaneous system. 

2d. They are mostly or entirely situated in more or less perfect bony 
cavities. 

3d. They are prolonged outward by valvular folds of the skin, which 
are provided with simple glands and hairs. 

4th. There is only one or at most but two : in the former case they 
are situated so that the median line divides them into two equal parts \ 
in the second there is only one on each side, a right and a left. 

As the direct organ of the spiritual principle is that which we consi- 
dered last, it is most convenient to examine first the organ of the most 
intellectual sense, that of hearing, and next to treat of that of sight, 
that of smell, and lastly the organ of taste, which forms a part of the 
digestive apparatus. After describing this apparatus we shall pass to 
the organs of respiration and of voice, then to those of the urinary se- 
cretion, and lastly to those of generation and the history of the fetus. 



SECTION I. 



OF THE ORGANS OF SENSE. 

§ 1902. All the organs of the senses{\) are similar in the following 
characters : 

1st. They are situated in the head. The organ of hearing is placed 
the farthest backward and belongs entirely to the skull ; it is also 
situated the most on the side, and its two lateral portions are entirely 
distinct from each other. The cavity occupied by the eye is partly 
formed by the bones of the skull and mostly by those of the face. 
That of the olfactory organ belongs still more to the face, in fact al- 
most exclusively to it, since the ethmoid bones form less of the skull 
than of the face. The cavity of the mouth is formed only by the bones 
of the face. The right and left portions also gradually approach each 
other from the organ of hearing to that of taste, so that they finally 
blend in the tongue. 

2d. They are all connected by short and large nerves with the ence- 
phalon. The auditory is proportionally the shortest and largest nerve. 
It arises from the calamus scriptorius as from a distinct cavity, so that 

(1) A. Molinetti, Disscrtationcs anatomicce ct pathologicce de sensibus ct eorum or- 
ganis, Padua, 1669. — Casscrio, Pantccstltcsejon, hoc eat de quinque sensibus liber 
orgarwrum fabricam, usum et actionem corn 'inert.?, Venice, 1699. — Haller, De sensibus 
in genere, Gotting-en, 1742.— Lecat, Traite des sens, Amsterdam, 1744.— Scemmer- 
ring, Abbildungcn der menschlichcn Sinnorganc, Francfort, 1809. 



OF THE EAR. Ill 

no other nerve of the organs of sense is connected so intimately -with 
the mass of the encephalon. 

3d. Ml receive their nerves from at least two pairs. The larger 
nerve is termed the nerve of sense, and the smaller the accessory nerve. 
In the organs of hearing, smell, and taste, the nerve of sense forms as 
many distinct pairs, the auditory, optic, and olfactory nerves, while in 
that of taste it is only a branch of the trifacial nerve, which is also the 
common trunk of the accessory nerves ; but this includes also the 
hypoglossal, the glosso-pharyngoeal and the facial, the three motor 
and the ganglionnary nerves. The names of several of these nerves 
prove that the accessory nerves serve principally to excite the motions 
of the organs of sense. The olfactory nerve is the only one which is 
to a certain extent an exception to the rule, since its proper accessory 
nerves, like its nerve of sense, are distributed in the mucous membrane 
of the nose. The nerves of sense and the accessory nerves are not 
necessarily connected" ; these connections do not exist in the organs of 
sight and hearing. They are slight and probably inconstant in the 
organ of smell, and are well developed only in the tongue, which is 
the most similar to the general organ of touch. 

4th. The proper nerves of sense expand more or less evidently as a 
thin membrane, which is covered directly by a fluid above which is a 
tissue similar to the epidermis. 

5th. They all communicate by ducts more or less broad, the prolon- 
gations of the internal cutaneous membrane which make part of them, 
and which perform a part as much more important in their organiza- 
tion the less they are developed. The more similarity there is between 
them, as between the organs of taste and smell, the more loose and ex- 
tensive the communication, so that so they really form but one in the 
early periods of life, at which time the roof of the palate which will 
separate the last two from each other is not yet formed. The com- 
munication between these two organs of sense and the others is more 
marked the nearer the fetus is to its period of formation. 

In fact the cutaneous system is more or less evidently the prototype 
of all the organs of sense, and the external integuments* are the seat of 
sensation, as the hand is that of the special modification of the general 
sensation termed the touch. 



CHAPTER L 

OP THE ORGAN OF HEARING. 

§ 1903. The organ of hearing, (I) or the ear, is situated at the 
centre of the side and the base of the skull within and on the surface 

(1) Fallopius, in his Obs. anat., Venice, 1561 ; Opp. omn., vol. i., tr. ii— Eustacbius, 
De auditus organo ; in the Opusc. anat., Venice, 1564.— Fabricius d'Aquapcndente, 



112 DESCRIPTIVE ANATOMY. 

of the temporal bone. This organ, the most noble and the most intel- 
lectual of the senses, belongs entirely to the skull. It is connected 
with the encephalon more directly, and is protected better against ex- 
ternal injuries than any other of the senses. 

It is formed of a considerable number of parts differing very much in 
their form and texture, and which may be divided generally into two 
sections, comprehending the external and the internal ear. 



ARTICLE FIRST. 



EXTERNAL EAR. 

§ 1904. The external ear, oricule, Ch. (auris externa), (I) is formed 
by the cartilage of the ear, the cartilaginous portion of the external 
auditory passage, and several muscles which are attached to the dif- 
ferent regions of the auricular cartilage. All these parts are covered 
by the common integuments. 

A. CARTILAGE OF THE EAR. 

§ 1905. The cartilage of the ear (cartilago auris),(2) considered 
generally, is formed like a short tunnel with a broad oval opening 
larger from above downward than from before backward. This sur- 
face is very uneven from several prominences and depressions which 
circumscribe this opening. 

De visione, voce et auditu, Venice, 1688. — J. Mery, Description exacte de I'oreille, 
E J aris, 1681. — Duverney, Traite dc Vorgane de I'ouie, contcnant la structure, les 
usages et les maladies de toutes les parlies dc I'oreille, Paris, 1683. — C. G. Schel- 
hammer, De auditu liber anus, Lcyden, 1684. A. M. Vasalva, Tractatus de aure 
humana, Bologna, 1704. — R. Vieussens, Traite de la structure de I'oreille, Toulouse, 
1714. — J. F. Cassebobm, Tractatus quatuor de aure humana, Halle, 1734; Trac- 
tatus quintus et scxtus, Halle, 1735. — Morc-agni, Ep. anat., cp. iv., v., vii., xii., xiii. 
— Geoffroy, Dissertations sur Vorgane de I'ouie de I'homme, des reptiles et de* 
poissons, Amsterdam, 1788. — C. P. C. Wildberg, Versuch ciner anatomisch-physiolo- 
gisch-pathologischen Abhandlung vber die Gehdrwerkzeugc des Mensctien, Jena, 
1795. — Scemmerring, Abbindungen der menschlichen Gehdrorgane, Francfort, 1806. 
— J. S. Schroeter, Das mcnschlichc Ohr, nach den Abbildungen Scemmerrings ver- 
grdsscrt dargestellt, Weimar, 1811.— J. Cunning-ham.— Saunders, The anatomy of 
the human car, illustrated by a series of engravings of the natural size, with a trea- 
tise on the diseases of that organ, the causes of deafness, and their proper treatment, 
1817. — C. S. Pohl, E.rpositio generalia anatomicu organis auditus per classes ani- 
■malium, Vienna, 1818.— T. H. Weber, De aure et auditu hominis el animalium, 
Leipsic, 1820. — J. Van der Hoeven, Diss, de organo auditus in homine, Utrecht 
1822. 

(1) D. Santorini, Dc aure interiori ; in (he Obsrrrat. analom., Venice, 1724, ch. 
ii. 

(2) B. S. AlbimiS; De cartilaginc auriculae; in the Annot. academ., lib. vi., cap. 
vii., tab. iv. 



OF THE EAR. 113 

1st. The most external eminence which mostly surrounds all the 
others is called the helix. 

It begins at the centre of the anterior edge of the external ear, goes 
first from below upward to the upper extremity of the auricular car- 
tilage, then curves backward, and finally descends to the posterior part 
of the circumference of the ear and terminates imperceptibly at its 
lower extremity. 

2d. A second eminence surrounded by the preceding, and termed 
the anthelix. It begins below and behind near the lower extremity of 
the helix, goes upward and forward, separates a little from this latter 
and divides at its upper and anterior extremity into a superior and an 
inferior branch, which extend to near the ascending portion of the 
helix where they gradually terminate. 

3d. Opposite the commencement of the helix is a third square emi- 
nence which forms the anterior and inferior part of the cartilage of the 
ear. It is termed the tragus. 

4th. Opposite the tragus we observe posteriorly a similar promi- 
nence termed the antitragus, separated by a groove from the prece- 
ding. The helix and the anthelix terminate here. 

§ 1906. The depressions between these different prominences are : 

1st. The scaphoid or navicular fossa {fossa scaphoidea), a slight 
depression which is concave forward, convex backward, and which 
extends between the posterior part of the helix and anthelix. 

2d. The anonymous triangidar or oval fossa (fossa anonyma, s. 
triangularis, s. ovalis), which extends between the two branches of 
the anthelix. 

3d. The concha (concha auris), a deep cavity which serves as the 
entrance to the cartilaginous portion of the auditory passage. It is 
situated between the helix, the tragus, and the antitragus. 

4th. The groove of the ear {incisura auris), situated between the 
helix and the tragus. 

§ 1907. The lower part of the external ear or the lobule (auriculus, 
s. lobulus aurus), has no cartilaginous frame. It is only a simple pro- 
longation of the skin filled with fat and mucous tissue. 

The cartilage of the ear extends at its lower part into a semicanal, 
which is open above and is termed the auditory passage, the auricular 
or oricular channel (meatus auditorius cartilagineus). This canal com- 
mences at the anterior part of the external ear, where it is more or less 
covered by the tragus like a valve. Its direction is at first transverse 
from without inward, or even a little from below upward : it then be- 
comes in most of its course oblique from below upward and from before 
backward. It is terminated above by the long posterior root of the 
zygomatic process of the temporal bone, and below this root by some 
fibrous tissue. 

The cartilage of the auditory passage, which is only a prolonga- 
tion of that of the ear, is generally interrupted in some portions of its 
extent. 



114 DESCRIPTIVE ANATOMY. 

The principal space is in part where the direction of the passage is 
changed in the manner mentioned. There in fact the internal and 
external portions of its cartilage are not united above and below except 
by a narrow band. 

The cartilage also presents at its external part a second smaller 
band, which descends from its upper edge and extends along its an- 
terior wall. 

The cartilaginous auditory passage is much shorter from before 
backward, than from above downward. It is about an inch long, four 
lines high, and three broad. Its inferior part extends inward and down- 
ward some lines farther than the upper. 

It is attached to the adjacent parts of the temporal bone by a firm, 
short cellular tissue. Its internal orifice particularly unites to the as- 
perities of the external orifice of the bony portion of the auditory pas- 
sage, of which this cartilaginous portion is the continuation. 

§ 1908. The cartilage of the external ear is entirely covered on its 
external and its internal face by the skin which intimately adheres to 
its inequalities. It gradually becomes thinner from without inward, 
moister and more analogous to a mucous membrane. The entrance 
of the auditory passage is generally furnished with short thin hairs 
which are arranged very compactly. The skin which lines it usu- 
ally presents on its inner face a considerable number of broad rounded 
openings. These openings lead to a glandular and reddish layer, 
which surrounds them and secretes the tvax {cerumen aurium), a thick 
yellowish, viscous, very inflammable fluid, in which chemical analysis 
demonstrates a fatty oil, a peculiar albuminous and a coloring sub- 
stance^ 1) 

B. MUSCLES OF THE EXTERNAL EAR. 

§ 1909. The cartilage of the external ear is provided with several 
muscles(2) which are generally thin and small, and may be referred 
to two classes : one includes those which move the whole external ear, 
and thus contribute to change its situation and direction ; the other 
is composed of those which move only some of its parts, and modify 
more or less evidently its general form. 

I. MUSCLES WHICH MOVE ALL THE EXTERNAL EAB. 

§ 1910. These muscles are the attollens auricula, the retrahentes 
auricula, and the attr aliens auricula. 

(1) Berzelius observes {Djurkmei, vol. ii. p. 230) that the cerumen ought also to 
contain water, and it is not well proved that the albuminous substance is truly of 
this nature. Rudolphi considers the bitter principle of the cerumen to be the same as 
that of the bile. p rp 

(2) D. Santorini, 06s. anat., cap. i. tab. 1 ; cjusdem Tab. poslh., vol. i.— A F. 
Walter, Anatome ienuiorum musculorum corporis humani repctita, with thetabie of 
.Santorini. 



OF THE EAR. 115 



a. Attollens auriculae. 



§ 1911. The attollens auriculae, muscle, the superior auricular 
muscle, temporo oriculaire, Ch., the largest muscle of the ear, is thin 
and triangular. It arises from the centre of the aponeurotic envelop of 
the skull and the aponeurosis of the temporalis muscle, contracts from 
before backward, and is attached to the eminence of the auricular 
cartilage, which corresponds to the triangular depression between the 
two branches of the anthelix. 

It elevates the ear, particularly during the action of the occipito- 
frontalis muscle, as it arises from the median tendon of this muscle. 

b. Retrahentes auriculae. 

§ 1912. There are generally three retrahentes auriculas ox posterior 
auricular muscles, mastoido-oriculaires, Gh. Sometimes there are 
but two, more rarely four, the inferior of which is very thin. These 
muscles are always situated successively from above downward, are 
very small, thin, and elongated. They arise from the mastoid process, 
and are attached by short tendinous fibres to the centre of the external 
face of the ear, on the eminence which corresponds to the entrance of 
the auditory organ. 

Their inferior extremity is often blended with the occipitalis, or with 
the complexus or the sterno-cleido-mastoideus muscles. 

These muscles draw the ear backward, and slightly dilate the 
concha. 

c. Attrahens auriculae. 

§ 1913. The attrahens auriculae muscle, the anterior auricular 
muscle, zygomato-oriculaire, Ch., is also very small, but always a 
little larger than the preceding. It arises on the zygomatic process, 
goes backward and downward, gradually contracts, and is attached by 
a short tendon to the inferior and anterior transverse portion of the 
helix, which forms the commencement of this eminence. 

It carries the ear forward and upward. 

H. MUSCLES WHICH MOVE CERTAIN PARTS OP THE EXTERNAL EAR. 

§ 1914. The muscles which move certain parts of the external ear 
are extremely small and weak, particularly in civilized nations. Being 
used but slightly or not at all, they cannot modify the form of the ex- 
ternal ear, and may be considered as rudiments of those which are 
much more developed in animals. All are thin, and are attached by 
all their internal face to the part of the ear which they move. 

They are the tragicus, the antitragicus, the htlicis major, the helicis 
minor and the transversus auriculae- muscles. 



116 DESCRIPTIVE ANATOMT. 



a. Tragicus muscle. 

§ 1915. The tragicus muscle, tragien, Ch. is oblong. It arises 
from the inferior and anterior part of the concha, directly below the 
tragus, which it covers outwardly. Its superior edge is situated below 
the lower extremity of this eminence. It rarely goes farther, and ex- 
tends to the lower extremity of the anterior edge of the helix, in which 
case it is even blended with the helicis major muscle. 

It carries the tragus outward, and thus shows the orifice of the 
concha. 

b. Anti-tragicus muscle. - 

§ 1916. The anti-tragicus muscle, antilragien, Ch. arises from the 
upper extremity of the external face of the antitragus, and is attached 
to the lower extremity of the anthelix. 

It approximates these two eminences, and carries the anti-tragus a 
little backward and outward. 

c. Helici3 major muscle. 

§ 1917. The helicis major muscle, grand helicien, Ch., is elongated. 
It arises from the inferior extremity of the helix, and ascends on the 
external and anterior face of this eminence, to which it is attached di- 
rectly above the point where the ear separates from the head. 

It draws the anterior part of the concha a little backward and 
downward. 

d. Helicis minor muscle. 

§ 1918. The helicis minor muscle, petit helicien, Ch., is the smallest 
muscle of the external ear. It is situated like the preceding, on the 
external face of the helix ; it arises much lower and more posteriorly 
than it, in the place where this eminence leaves the external ear, and 
is attached sometimes higher to its ascending portion near the pos- 
terior edge. 

It slightly depresses the anterior part of the helix. 

e. Transversus auricula muscle. 

§ 1919. The transversus auricula muscle, transverse de I'oricule, 
Ch., is situated on the internal face of the external ear, viz. that which 
looks towards the head. It is larger than the preceding, but is formed 
of fasciculi which are less coherent, and generally also less evidently 
fleshy. Its direction is transverse in almost all its course, and it ex- 
tends from the anthelix to the scaphoid fossa. 

It draws the scaphoid fossa and the helix outward, and thus en- 
larges the opening of the ear. 



OF THE EAR. 117 



ARTICLE SECOND. 

INTERNAL EAR. 

§ 1920. The internal ear (auris interna){\) comprehends : 

1st. A considerable portion of the temporal bone, especially the 
petrous and mastoid processes. 

2d. The small bones of the ear, which moveably articulate with the 
temporal bone. 

3d. The muscles whic?i move these little bones. 

4th. A cartilaginous channel by which the ear communicates with 
the cavity of the mouth. 

5th. A fibro-cartilaginous expansion contained within the bony por- 
tion of the ear. 

6th. The auditory nerve which is distributed to this expansion. 

A. EXTERNAL PORTION. 

I. OSSEOUS PORTION OF THE AUDITORY PASSAGE. 

§ 1921. The osseous portion of the auditory passage, conduit 
auriculaire, s. oriculaire, Ch. (meatus auditorius osseus), when per- 
fectly developed, forms the posterior and external part of the lower face 
of the petrous process of the temporal bone. It is an elliptical canal, 
the direction of which is from above downward, from behind forward, 
and from without inward, which gradually contracts in the same di- 
rection. This canal is about half an inch long. Its height exceeds its 
breadth. 

Its external orifice which presents grooves and asperities on its 
edge, is called the external auditory foramen (poms acusticus externus, 
aditus ad meatum auditorium osseum) . It is turned from within out- 
ward, and is intimately united to the cartilaginous portion of the audi- 
tory passage. 

Its posterior wall is a little shorter than the anterior. It is lined in 
its whole extent by a prolongation of the skin which covers the ear, 
and which gradually becomes thinner from without inward. 

Its internal orifice presents a considerable depression, a groove in 
which the membrane of the tympanum is situated. This groove ex- 
tends all around it, except its upper portion. 

(1) C. Folius, Nova auris interna; delineatio, Venice, 1645. — B. S. Albinue, De 
aure humana anteriore; in the Annot. acad., book iv., cap. ii. — A. Comparetti, Ob- 
servationes anatomiccs de aure interna comparata, Padua, 1789. — A. Monro, On the 
brain, the eye and the ear, Edinburgh, 1797. — Ribes, Mimoire siir quelques parties 
de Voreille interne; in the Bulletin de lasoc. med. d'emul., 1823, November, p. 650 
December, p. 707. 

Vol. III. 16 ' , 



118 DESCRIPTIVE ANATOMY. 



II. MEMBRANE OF THE TYMPANUM. 

§ 1922. The membrane of the tympanum (mem. tympani),(l) which 
is inclosed in the internal orifice of the auditory passage, separates the 
canal from that part of the internal ear which is next to it, that is from 
the cavity of the t3 r mpanum. 

It is a thin, elliptical membrane, the direction of which is a little 
oblique from above downward, from without inward, and from behind 
forward. There is positively no opening in it in the normal state, 
although the contrary opinion has been maintained in several different 
forms. (2) It consequently completely separates the cavity of the tym- 
panum and the labyrinth from the osseous portion of the auditory 
passage and from the external ear. As it extends a little farther than 
the opening which receives it, its form changes in regard to its degree 
of tension and relaxation, (3) which is produced principally by the ac- 
tion of the muscles of the little bones of the ear. It fits exactly into 
the groove at the internal extremity of the auditory passage. 

Anatomists differ in opinion in regard to the formation of the mem- 
brane of the tympanum. The most correct consider it formed of a 
special membrane situated in the centre, of a second which is external, 
situated next to that of the bony portion of the auditory passage. 
In this view of the subject the external layers would be culs-de-sac of 
the internal and the external cutaneous system, while the middle 
layer forms a distinct and special membrane arising from the bony 
portion of the auditory passage. 

This special membrane presents very distinct fibres which radiate 
from its centre to its circumference, and are very manifest in its internal 
face. Judging from analogy, that is from what occurs in the large 
animals particularly the elephant, these fibres are probably muscu- 
lar. (4) The most careful injections demonstrate also numerous blood- 
vessels which come principally from two circular trunks, an external 
and an internal, and which anastomose together frequently. 

(1) A. F. Walther, De membrana lympani, Leipsic, 1725. — Brugnone, Observa- 
tions anatomiques sur la structure de la membrane du tympan et de cellc de la caissc ; 
in the Mem. de Turin, an. xii., p. 1,12.— E. Home, in the Phil, trans., 1804. 

(2) Very recently even Vest, judging- from his own observations and those of 
Wittmann, has maintained the normal existence of an opening in the membrane of 
the tympanum, admitted some time since by Rivinus, and long neglected. He 
asserts that this opening is oblique, and thus forms a kind of valve. But he admits 
it is frequently deficient ( Uuber die Wittmann' sche Trommeljellklappc ; in the 
Medicinische Jahrbiicher des Oesterreichischen Staates, vol. v., Vienna, 1819, p. 
123-133). To conclude from a few cases, which were probably morbid, that the 
opening is formed primitively, is evidently to make the exception a rule. F. T. 

(3) F. Savart, Recherches sur les usages de la membrane du tympan et de I'oreille 
externe ; in the Journal de physiol. experiment., vol. iv., p. 183. 

(4) Sir E. Home asserts he has found some muscular fibres in the membrane of the 
tympanum in the elephant. Their existence is at least doubtfnl. Rudolphi has 
observed nothing similar in the whale or horse. p_ x. 



OF THE EAR. 



119 



Of the two superficial layers the external is easily insulated : but it 
is more difficult to separate the internal from the middle, both on ac- 
count of its fineness and because it adheres to this latter more inti- 
mately. 



B. MIDDLE PART. 



I. TYMPANUM. 



§ 1923. The tympanum or the drum (tympanum, s. cavitas tym- 
pani)(\) is a narrow, rounded cavity, which is generally convex inter- 
nally and which is continuous outwardly with the osseous portion of 
the auditory passage by a broad opening before which the membrane 
of the tympanum is expanded, and forward with the Eustachian tube 
through another narrower opening. This cavity forms the central 
part of the internal ear ; hence some anatomists term it the middle ear, 
in opposition to the labyrinth and all the parts on the outside of it. It 
occupies the external and posterior part of the petrous portion and 
communicates anteriorly with the cavity of the mouth, posteriorly with 
the mastoid cellules. 

Its internal and very irregular face presents numerous elevations 
and depressions which are connected with the labyrinth. It incloses 
the little bones of the ear and the cord of the tympanum. 

When we consider only the bones, we perceive that it is open for- 
ward, backward, and downward. A mucous membrane which is 
continuous with that of the throat lines its whole extent. 

§ 1924. On the inner face of the cavity of the tympanum, forward 
and downward, at about its centre is a considerable eminence, termed 
the promontory (promontorium), formed by the commencement of the 
cochlea, and always covered by osseous substance. 

At its lower and posterior part is an oblong, triangular opening, more 
high than broad, which is directed backward and outward ; this is the 
fenestra rotunda, the cochlear opening of the tympanum.(2) This 
opening communicates with the cochlea, but it is closed by the mu- 
cous membrane which lines the whole cavity of the tympanum. (3) 

Above the promontary and a little above the centre of the tympa- 
num is a second and much larger opening, called the fenestra ovalis, 
the vestibular opening of the tympanum (fenestra ovalis, s. semi-ovalis). 
The length of this opening, the greatest diameter of which is directed 
from above downward and from before backward, exceeds its breadth. 

(1) Santonin, Opp. posth., tab. v. 

(2) A. Scarpa De structur a fenestra, rotnndoe auris, et de tympano secundaria 
anatomicce observationes, Modena, 1772. — Ribes, loc. cit., p. 652. 

(3) Ribes asserts that the membrane of the fenestra rotunda is composed of a 
special layer, of a second given off by that of the cavity, and of a third coming 1 from 
that which lines the internal scala of the cochlea. Its structure then resembles that 
of the membrane of the tympanum. F. T. 



120 DESCRIPTIVE ANATOMV. 

Its posterior edge is convex, the anterior is straight. It is surrounded 
outward by a small groove. 

On the posterior wall of the cavity of the tympanum opposite the 
lower extremity of the fenestra ovalis, farther backward and much 
more outward, we remark the pyramid (eminentia pyramidalis), a small 
triangular eminence which terminates forward by an opening which is 
grooved in it, and which communicates with the Fallopian canal: 
from the anterior extremity of this a small bridge of bone is frequently 
detached, which goes to the upper extremity of the promontory, below 
the fenestra ovalis. 

Below and more posteriorly is another opening (apertura chords) 
through which the cord of the tympanum passes from the Fallopian 
canal to the tympanum. 

The space between the pyramid, the promontory, and the fenestra 
ovalis forms a considerable depression termed the sinus of the tympa- 
num (sinus tympani). 

Above and in the centre the cavity of the tympanum is grooved to 
receive the upper part of the two largest bones of the ear. 

Upward and backward it communicates by one or more considera- 
ble openings with the cavity of the mastoid process, which must con- 
sequently be considered as a prolongation of it. This cavity is divided 
by numerous septa into cellules, which enlarge much from the centre 
to the circumference, and which are lined by the mucous membrane 
which covers the inner face of the tympanum. 

The internal wall of the tympanum presents at its anterior part a 
groove which leads into an osseous prolongation ; this extends forward, 
and is the bony portion of the Eustachian tube {tuba Eustachii ossea). 
Above this groove we observe a second, which sometimes is not sepa- 
rated from the other in its whole extent, and which lodges the tensor 
tympani muscle. 

Under the posterior extremity of the second groove is a small open- 
ing which leads above to the superficial petrous groove, below to a 
groove which descends on the promontory. This groove becomes 
at its lower part a canal which opens outward on the lower face of 
the pyramid, between the carotid canal and the fissure of the jugular 
vein. 

Through this canal passes a filament of anastomosis between the 
second branch of the trifacial, the glosso-pharyngceal, and the gan- 
glionnary nerve; this minute filament arises from the superficial 
petrous nerve, enters the cavity of the tympanum with another fila- 
ment of the great sympathetic nerve, and communicates below this 
cavity with the ganglion of the glosso-pharyngceal nerve.(l) 

(1) Jacobson, Supplemented ad otoiatriam; in Act. Hafn., vol. v., 1818, p. 292. 



OF THE EAR. 121 



II. EUSTACHIAN TUBE. 



§ 1925. The Eustach'an lube, conduit guttural de foreille, Ch. 
(tuba Eustachii), is a canal the posterior part of which is formed of 
bone, but is fibrous and fibro-cartilaginous at its anterior portion, and 
extends from the tympanum to the upper part of the pharynx. The 
direction of this canal is oblique from above downward, from without 
inward, and from behind forward. It is nearly two inches long. 

The osseous portion is the shortest, and is situated above the carotid 
canal. It becomes narrow from behind forward. 

The cartilaginous portion proceeds directly below the base of the 
skull, but on the contrary gradually enlarges in the same direction. 
It is compressed from within outward in its whole extent. Its form is 
elliptical and it is fibro-cartilaginous in the inner portion and sometimes 
also in the upper portion of its external wall. In other parts it is com- 
posed of a fibrous tissue which arises from the periosteum of the infe- 
rior pterygoid process. 

The Fallopian tube is entirely lined internally by a very fine mucous 
membrane which is continuous with that of the oral cavity and of the 
tympanum. Around the buccal orifice of this tube this membrane 
becomes much thicker, partly from a great development of the muci- 
parous glands. Thence a prominence is formed which changes this 
opening into a narrow longitudinal fissure and forms a kind of valve. 



III. BONES OF THE EAR. 



§ 1926. The bones of the ear (ossicula auditus),(l) situated at the 
ripper part of the cavity of the tympanum, are the smallest bones in 
the body. They form a chain composed of pieces movably articu- 
lated with each other, which extends from the membrane of the tym- 
panum to the fenestra ovalis, consequently to the labyrinth, and which 
conveys to the deepest parts of the internal ear the changes which 
supervene in the membrane of the tympanum. 

There are three bones, the hammer (malleus), the anvil (incus), and 
the stirrup (stapes) ; and in the early periods of life a fourth, the lenti- 
cular bone. 



(1) J. A. Schmid, Deperiostoo ossiculorum audilus ej usque vaseculis, Leyden, 1719. 

H. F. Teichnieyer, Diss, medica solemnis sistens vindicias quorundam inventorum 

anatomicorum, Leipsic, 1727.— Magcndie, Sur les organes qui tendent oureldchent 
la membrane du tympan et la chaine des ossclcls de I'ouie dans I'homme et dans les 
animaux mammiferes ; in the Jour, dephys. experm., vol. i., p. 341-347, tab. iv. 



122 DESCRIPTIVE ANATOMY 



a. Malleus. 

§ 1927. The hammer {malleus) forms the anterior and external part 
of the chain, and is divided into a head, a neck, a handle, and pro- 
cesses. 

The head, the tipper part, is rounded, oblong, convex and smooth 
forward, concave and slightly uneven backward. Its posterior face is 
oblong and surrounded by a slightly prominent edge. A transverse 
eminence divides it into an upper and a lower face. 

The head is situated above the inferior edge of the membrane of the 
tympanum in the anterior part of the upper prolongation of the cavity 
of the tympanum. 

The neck is short, compressed in all parts, but particularly slightly 
flattened from without inward. 

Its lower extremity is divided into three sections, the handle and the 
two processes. 

The handle (manubrium), or the inferior section, descends a little 
from without inward and from behind forward. It is terminated at its 
lower extremity by a small prominence, and is situated between the 
layers of the membrane of the tympanum. 

The external or the short process (processus externus, s. obtusus, s. 
brevis) projects more or less at the upper extremity of the handle, and 
forms with it a right angle. It is directed outward, and is separated 
by a deep groove from the head, into which the upper side of the in- 
ternal extremity of the auditory passage enters. 

The anterior long or spinous process (processus anterior, s. longus, 
s. spinosus) is thinner but much longer than the preceding, and is con 
vex above and concave below. It is received by a broad and super- 
ficial groove hollowed on the inner face of the upper extremity of the 
ring of the tympanum. 

The malleus is connected with the membrane of the tympanum and 
with the incus. 



b. Incus. 

§ 1928. The anvil (incus) has nearly the form of a bicuspid molar 
tooth ; it is composed of two branches and of a centre which may be 
termed the body. 

The body is almost square, flat, and presents forward a concave 
face by which the bone articulates with the head of the malleus 
(§ 1926). It is situated above the membrane of the tympanum. 

The upper or posterior and shorter branch is flattened from within 
outward, terminated by a blunt summit also situated above the mem- 
brane of the tympanum, and is directed horizontally from before back- 
ward where its loose extremity terminates. 



OF THE EAR. 123 

The anterior or inferior branch varies in length and is almost 
straight ; its direction is from above downward and from behind for- 
ward, and it is situated more internally than the preceding. It termi- 
nates in a small button-like prominence ; it is situated behind the 
handle of the malleus, a little on the outside of it. 

The body of the incus articulates above and forward with the head 
of the malleus, by its long branch below with the stapes. It is not di- 
rectly connected with the membrane of the tympanum. 

c. Lenticular bone. 

§ 1929. The lenticular bone (os lenticulare, s. Sylvii) is an ex- 
tremely small, flat, and rounded bone, situated on the inner face of the 
lower extremity of the long branch of the incus. It generally fuses 
with the incus very early, even during the latter months of pregnancy, 
and then forms an eminence which projects on its inner face. 

d. Stapes. 

§ 1930. The stirrup (stapes) is situated more internally than the 
other two bones of the ear, and is not perpendicular like them but hori- 
zontal. It is composed of a head, two branches, and the transverse 
face or the base. 

The head is rounded, oblong, and flattened from above downward. 
Its upper extremity looks outward and presents a slight depression for 
the lenticular bone : the two branches are sometimes separated by a 
contracted neck. 

The anterior branch is always shorter and also straighter than the 
posterior branch. Both are grooved on their internal faces, which look 
towards a groove in which a membrane, a prolongation of that of 
the tympanum, extends between them. 

The base has exactly the same form as the fenestra ovalis, with 
which it is movably united by the membrane of the tympanum. It 
is always a little narrower, so that it can enter and leave the vestibule 
through this opening. 

Its inner face, which corresponds to the fenestra, is straight. The 
external is concave and circumscribed by prominent edges. 

IV. MUSCLES OF TH5 BONES OF THE EAE. 

§ 1931. The small bones of the ear are moved by four muscles, 
which, like the bones to which they are attached, are the smallest in 
the body. Three of these are inserted in the malleus and one in the 
stapes. Two muscles of the malleus are situated before the cavity of 
the tympanum, the third above this cavity. That of the stapes is 
situated behind it. The incus has no special muscle : it forms only a 
connecting link between the.malleus and the stapes. 



124 DESCRIPTIVE ANATOMi'. 



a. Muscles of the malleus. 

6 1932 The three muscles of the malleus from their connections of 
the bone with the membrane of the tympanum vary the degree of 
tension of this membrane. They are distinguished into an internal and 
an external. 

1. Tensor tympani muscle. 

§ 1933. The tensor tympani muscle, the internal muscle of the malleus 
(m. tensor tympani, s. mallei internus) is elongated. It arises from the 
upper part of the cartilaginous portion of the Eustachian tube near the 
sphenoid bone, and generally comes from its large wing. Its direction is 
from before backward in the canal from which the petrous process is 
grooved to allow it to pass to the osseous portion of the tube. In the 
cavity of the tympanum the direction of its tendon changes, leaves the 
internal wall of this cavity, goes outward and is attached to the upper 
extremity of the inner face of the malleus directly below its long 
process. 

This muscle draws the malleus inward, tenses the membrane of the 
tympanum which the bone draws with it, and brings the chain of bones 
inward so as to sink the stapes into the fenestra ovalis. 

2. Laxator tympani major muscle. 

§ 1934. The laxator trjmpani major muscle, the great external 
muscle of the malleus (JVf. laxator tympani major, s. mallei externus 
major), arises from the grooved prolongation of the great wing of the 
sphenoid bone, and is directed from without inward and from before 
backward. Its tendon enters the fissure of Glaser and is attached to 
the long process of the malleus. 

It draws the malleus forward and outward, and thus relaxes the 
memtrane of the tympanum. 

3. Laxator tympani minor muscle. 

§ 1935. The laxator tympani minor muscle, the small external mus- 
cle of the malleus (JVf. laxator tympani minor, s. mallei externus minor), 
is much smaller than the two preceding and arises from the upper edge 
of the osseous portion of the auditory passage, passes between the 
layers of the membrane of the tympanum, goes forward and outward, 
and is attached sometimes higher and sometimes lower to the handle 
and the external process of the malleus. 

It draws the malleus upward, backward, and outward. It conse- 
quently relaxes the membrane of the tympanum. 



OP THE EAR. 125 



b. Stapedius muscle. 

§ 1936. The stapedius muscle (M. stapedius) is oblong and trian- 
gular. It arises at the base of the pyramid and goes forward and 
upward. Its tendon comes through the anterior opening in the top of 
the pyramid, and is attached to the posterior part of the head of the 
stapes. 

It draws the stapes backward so as to bring the posterior portion 
of its base into the fenestra ovalis. It also draws the chain of the 
bones inward, and thus tenses the membrane of the tympanum. 

We have every reason to think that it acts at the same time as the 
tensor tympani muscle. 

C. INTERNAL PORTION OR LABYRINTH. 

§ 1937. The labijrinth (labyrinthus),(\) the most internal part of 
the organ of hearing, comes next inside to the tympanum. It is a 
double cavity situated in the petrous portion of the temporal bone, di- 
rectly surrounded by the very firm substance of this portion, and is 
formed of several compartments of very complex figures. We distin- 
guish in it a central part the vestibule, a posterior part the semicircu- 
lar canals, an anterior portion the cochlea, and the lateral parts the 
aqueducts. 

One of the two cavities which form it completely surrounds the 
other and is moulded upon it. 

The first is the osseous labyrinth, the second the membranous laby- 
rinth. 

I. OF THE OSSEOUS LABYRINTH. 

§ 1938. The osseous labyrinth in the adult is not distinct from the 
compact substance of the petrous process of the temporal bone, of 
which it forms the most internal, the firmest and the hardest part, 
which closely envelops and covers the membranous labyrinth. But 
in the early periods of life it is formed by a solid, hard, and brittle sub- 
stance, separated from the external layer of the petrous process by a 
less compact osseous tissue. Its internal face is moistened with limpid 
serum which exactly fills all the space between it and the membranous 
labyrinth.(2) 

During the early periods of life we find between the two labyrinths 
a membrane which is not the periosteum of the osseous portion, al- 
though generally considered as such, but which belongs to the class 

(1) A. Scarpa, Disquis. anatomicce de auditu et olfactu, Pavia, 1789. — A. Monro, 
loc. cit. — Brugnone, Observations anatomico-physiologiques sur le labyrinthe de 
Voreille ; in the Memoires de Turin, 1805-1808, p. 167-177. 

(2) Cotugno, Din. cit., § xxix.— P. F. T. Meckel, Dc lahyrinthi crnris ronteniis, 
Straflburg', 1777. 

Vol. IIT. 17 



126 DSSCR1FTIVE ANATOMY. 

of sero-mucous membranes. This is demonstrated by the numerous 
ressels it receives and by its abundant secretion and its connections 
with the membrane of the tympanum. 

a. Vestibule. 

§ 1939. The vestibule (vestibulum),(l) the middle of the bony laby- 
rinth, is situated farther inward and more posteriorly than the tym- 
panum. It is of a rounded and oblong cavity at about the centre of 
which we perceive the internal orifice of the fenestra ovalis. We there 
remark principally two small depressions or superficial grooves, one 
superior, posterior and external, more extensive than the other and of 
an oval form (fovea, s. cavitas ovalis, s. elliptica, s. semi-elliptica) ; the 
other inferior and anterior, smaller and semicircular (fovea hemi- 
sphcerica, s. orbicularis). The first is situated on the posterior and 
inferior wall, the second on the superior and external. They are 
separated by a sharp crest which extends from above downward. 

The oval fossa is continuous below with another which is smaller, 
the sulciform groove (fovea sulciformis) . 

§ 1940. In the circumference of the vestibule are six large foramina 
and one which is rounded and very small. 

Of these six large foramina, one which occupies the anterior and 
inferior part of the vestibule leads to the superior scala of the 
cochlea ; the other five situated at the posterior part are the orifices of 
the posterior part of the labyrinth or the semicircular canals. 

The small opening at the posterior and inner part of the vestibule in 
the sulciform groove leads to the aqueduct of the vestibule. 

• 

b. Semicircular canals. 

§1941. The semicircular canals (canales semi-circulares) form the 
posterior and largest part of the labyrinth. 

There are three of them which occupy a square space : the superior 
or anterior, the posterior, internal or inferior, and the external. The 
first two are perpendicular, the third is horizontal. 

When united they form more than half a semicircle. They are 
much more prominent at one of their extremities than at the other and 
in the rest of their course, so that they represent in this place a rounded 
vesicle (ampulla). They are not perfectly round externally nor inter- 
nally, but are slightly flattened and elliptical. 

The diameter of their cavity is about half a line. 

Their orifices are a little broader than the rest of their course. 

The superior is oblique from without inward and from before back- 
ward. It forms the highest part of the labyrinth, and its two branches 
are separated the farthest. Its anterior and external opening, which 

(1) Ribee, loc. cit., p. 661. 



OF THE BAR. 127 

is situated above the fenestra ovalis, forms a considerable vesicle of 
which we see another trace at its posterior extremity, through which 
it blends with the superior opening of the internal canal. 

The inferior is also perpendicular, but its convexity looks backward 
and its concavity forward. It commences above by a short canal 
which it has in common with the internal extremity of the superior, 
and terminates by a vesicular enlargement below and inward in the 
vestibule. 

It is the longest and its branches are nearest each other. 

The external or horizontal arises by a slightly marked vesicular 
prominence below the external orifice of the superior. Its internal 
orifice in the vestibule is situated on the outside and below the com- 
mon opening of the superior and the inferior. 

It is the shortest and also the broadest of the three semicircular 
canals. 

The reunion which occurs between the superior and inferior canal 
diminishes the number of the openings of the semicircular canals to 
five instead of six. 

c. Cochlea. 

§ 1942. The cochlea(l) forms the anterior and most complex part 
of the labyrinth. It presents to a certain extent the repetition of the 
semicircular canals, and its figure perfectly resembles that of the shell- 
fish whose name it bears. 

It is a grooved canal which gradually diminishes from its origin to 
its extremity, and thus it finally becomes very narrow. It turns 
around a central and perpendicular portion termed the axis (modiolus), 
which gradually becomes thinner. It thus describes two turns and a 
half. 

The first turn is much larger than the rest, which it envelops ; the 
others however project much beyond it. 

§ 1943. A horizontal plate of bone, which arises from the inner part 
of the cochlea and which is termed the spiral septum (lamina spiralis), 
divides it into two canals situated one above the other and termed the 
scaloz. 

The lower face of the spiral septum presents grooves which look 
towards the axis. Its upper face is the smoothest. 

It is formed of two laminae, a superior and an inferior. 



(1) G. Brendel, De auditu in apice cochlea, Program. I. II, Gottingen, 1747. — J. 
G. Zinn, Obscrvationes de vasis *ubtilioribu3 oculi et cochlea auris internee, Got- 
tinfren, 1753.— J. G. llg-, Einige anatomische Bemerkungen, enthaltend einc Be- 
richtigung der zeitigen Lehre vom Ban der Schnecke des menschlichen Geh'oror- 
gans y nebst einer anatomischen Beschreibung und Abbildung eines durck ausseror- 
dentliche knochenwucherung sehr merkwiirdigen menschlichen SchadeU, Prague, 
1921. 



128 DESCRIPTIVE ANATOMY. 

The inferior lamina is much broader than the superior, and termi- 
nates backward and outward in the fenestra rotunda in the tympanum. 
This has been termed the scala of the tympanum (scala lympani). 
It is separated from the cavity of the tympanum by a membrane which 
presents a depression on the side of this cavity which is termed the 
secondary tympanum (tympanum secundarium) . 

The superior scala is much narrower than the.inferior. It terminates 
at the anterior opening of the vestibule. Thence it is termed the scala 
of the vestibule (scala vestibidi). 

The cochlea however does not continue separated the entire length 
of this cavity, and the spiral septum terminates near the middle of the 
second turn in a pointed hook termed the hook of the cochlea (hamulus 
cochlear). 

By uniting in this manner, the two canals of the cochlea give rise to 
a tunnel-like cavity, the infundibidum (scyphus), the base of which is 
turned upward and the summit downward towards the cupola of the 
cochlea. 

This conical cavity forms the most prominent part of the cochlea. 

The axis(l) which turns on itself is hollow like the scalae. A larger 
canal passes longitudinally through it from its base to its summit. It 
also presents numerous small openings, the diameter of which gradually 
diminishes from its base to its summit. These openings lead to small 
canals which terminate on the spinal lamina. (2) 

(1) Rosenthal, Sur la structure de Vaxe du limacon dans Voreille de I'homme ; in 
the Journal comvlem. du Diet, des sc. mid., vol. xvi., p. 180. 

(2) Anatomists have hitherto considered the axis of the cochlea as a small column 
formed by a very thin osseous lamina, through which a canal passes from the base 
to the summit, which is perforated by numerous small foramina. It is asserted that 
it terminates at the second turn of the cochlea, at the top of which it appears on 
leaving 1 this place as a tunnel-form layer of bone, the summit of which is the termi- 
nation of the axis, and the upper extremity of which looks towards the summit of 
the cochlea and is covered by a plate of bone. Hence are distinguished the cavity of 
the axis and that of the infundibulum. There is also admitted in the latter a thin 
column around which the spiral septum turns from the second curve, and which 
terminates in a small osseous plate curved like a hook, llg describes the structure 
of this axis differently. He states that the spiral channels of the cochlea do not turn 
around a special nucleus of bone ; hence he does not admit an axis, but asserts that 
it is the inner and concave wall of the spiral canal which forms the species of column 
around which this canal turns, and that we perceive in it the form of a cylinder on 
opening the first and second turn of the cochlea. The column is very thick in the 
first turn where it is a line and a half in diameter, but very thin in the second where 
its diameter does not exceed half a line. As the internal wall of the spiral canal 
forms what is termed the axis in the first two curves, so likewise it produces some- 
thing similar in the third. But this pillar of the third turn has not the form of a 
cylinder ; it is composed only of a very thin and twisted osseous plate, which arises 
from the summit of the cylindrical column and extends to the cupola of the cochlea, 
where it is attached. The loose edge of this plate, which exists all the length of the 
imaginary axis of the cochlea, from the termination of the cylindrical column to the 
top of this cavity, is smooth, rounded, and generally a little concave in the direction 
of its length. Sometimes also it represents a small column which goes directly to 
the summit of the cochlea. The axis of the column is perforated by a small canal 
and this column is filled to the second turn by an osseous cellular mass, the cellules 
of which communicate with numerous small foramina grooved along the parietes of 
the column, and into which open some small canals which proceed between the two 
layers of the septum or spiral lamina. Rosenthal has since modified and rectified the 



OF THE EAR. 129 



d. Aqueducts. 

§ 1944. The aqueducts (aquceducius, diverticula, )(\) of the laby- 
rinth are short, narrow canals, which are directed from above down- 
ward through the substance of the petrous process of the temporal 
bone, and which enlarge a little in their course. There are two, the 
aqueduct of the vestibule, and the aqueduct of the cochlea. 

The aqueduct of the vestibule (aquceductus vestibuli) begins by a very 
small opening in the inner wall of the vestibule before the common 
opening of the two perpendicular semicircular canals in the sulciform 
groove of the vestibule, which is in fact their internal orifice. It first 
goes a short distance from without inward and a little from below up- 
ward in the centre of the petrous process, then from above downward, 
insensibly enlarges on leaving this curve, and after proceeding about 
four lines terminates a little behind the centre of the inner face of the 
petrous process of the temporal bone near the fossa intended for the 
gulf of the internal jugular vein, with which it always communicates 
by a slight groove. 

The aqueduct of the cochlea (aquceductus cochlea) commences by a 
wider opening in the tympanitic scala of the cochlea directly before 
the fenestra rotunda, descends from before backward, enlarges in this 
course, and terminates by a triangular opening at about the centre of 
the inferior edge of the petrous process of the temporal bone. 

By these two aqueducts the membranous labyrinth communicates 
externally, (2) and forms culs-de-sac between the bone and the dura- 
mater. 

description of Ilg. It follows from his researches, that from the summit of the pillar 
of the first two turns a layer proceeds in a semicircle to the external wall, and ter- 
minates by a loose and semilunar edge, which ascends to the infundibulum. The 
last turn is open on the side of this edge, by which the lamina turned opposite the 
pillar terminates, and the unciform extremity of the spiral lamina which is reflected 
around the same edge projects in the turn in question ; the two lamina; terminate in 
this place, or rather blend in this small rounded cavity. The crook turning around 
the edge of the lamina of the axis in the place where this lamina separates from the 
centre of the pillar, is like the extremity of the latter, separated from the infundi- 
bulum. The edges of the spiral lamina and of that of the pillar are fitted to each 
other, cross so that their fac.es are turned from the side of the external wall of the 
cocnlea, and as the latter inclines a little towards the centre of the pillar, they form 
in some measure a broad tunnel-like edge for the canal grooved in the first two 
turns of the column to emerge. It follows then from Rosenthal's description: 1st, 
that, as Scarpa and some other anatomists have asserted, the base of the infundi- 
bulum is situated on the summit of the cochlea and its summit in that of the pillar, 
but it does not extend so deeply as they assert, for it terminates below the last semi- 
turn and is loose below the cupola of the cochlea, and there is no extended lamina 
of the column which unites with its covering ; 2d, that Ilg is mistaken in saying 
that the axis extends to the centre of the cochlea, to its roof, and that it does not 
form a tunnel-like edge, and is attached to the summit of the cochlea by a rounded 
point closed at its extremity. F. T 

(1) D. Cotugno, De aquceductibus auris humance internee analomica dissertatio, 
Naples, 1761.— P. F. Meckel, De labyrinthi auris conlentis, Strasburg, 1777. — Ribea, 
loc. c«., p. 713. 

(2) The opinion that the aqueducts establish the communication between the la- 
byrinth and the exterior was admitted by Cotugno, who, thinking that the internal 



130 DESCRIPTIVE ANATOMY. 

They also serve for the passage of the arteries which enter the laby- 
rinth and the veins which come from it and the lymphatics, the ab- 
sorbent action of which prevents the abnormal accumulation of serum 
in this cavity. The veins, and perhaps some of the lymphatics also, 
empty into the internal jugular vein. This explains why mercury 
and other fluids pass from the labyrinth into this vein through the 
aqueducts, after distending the sacs of the membranous labyrinth. 

car is always exactly filled with serum, had been obliged to explain how this liquid 
can be moved by the compression exercised upon it by the base of the stapes to sup- 
pose the existence of derivative canals, which allow it to escape in part, and to leave 
a certain space between it and the parietes of the ventricle. The observations of 
Brugnone and of Ribes, which we shall mention hereafter, overturn all this theory. 
These anatomists consider the pretended aqueducts only as passages for the arteries 
and veins. In regard to that of the vestibule, Ribes has discovered that at about the 
centre of the posterior face of the petrous portion of the temporal bone, where it 
begins as an uneven and undulating layer, it goes forward, upward, and outward, 
proceeds first on the inside of the posterior semicircular canal, next between the 
posterior wall of the vestibule and the superior semicircular canal, curves and pene- 
trates into the concavity formed by this canal, thence goes backward and outward, 
and is distributed in the spungy tissue of the posterior part of the labyrinth. This 
duct is at first very broad, and it contracts much in its course upward. It generally 
gives off in its course other smaller ducts, at each of which it becomes smaller, and 
among which Ribes has found some which opened into the inner part of the vesti- 
bule, others into the posterior semicircular canal, but only in three pieces, for in all 
others there was no duct from the aqueduct proceeding either within the vestibule 
or to any other point within the labyrinth. Besides this aqueduct does not exist in 
the full grown fetus nor even some time after birth. It is designed to contain the 
blood-vessels which ramify in all the spongy tissue surrounding the labyrinth, and 
sometimes enter into the vestibule. Ribes asserts that the aqueduct of the cochlea 
arises at the base of a small depression situated about the centre of the lower edge 
of the petrous portion of the temporal bone, ascends obliquely to the lower part of 
the internal auditory passage, passes under the labyrinth, goes horizontally back- 
ward and outward, and terminates not in the internal scala of the cochlea, as is 
stated, but in the canal of the fenestra rotunda below the membrane which closes 
its opening. As this passage proceeds towards the tympanum it gives rise to nu- 
merous branches. It lodges the vessels which are distributed under the labyrinth 
in the spungy tissue of the petrous portion of the temporal bone and within the 
tympanum. Thus the two pretended aqueducts belong to the class of vascular 
canals described in a note on the osseous system. But there are others beside them 
observed in the petrous process. Ribes mentions three others : 1st, one which arises 
at about the centre of the posterior base of the petrous process near its upper edge 
and two lines from the internal auditory passage, goes backward and outward, 
passes under the anterior semicircular canal, opens directly under the curve of the 
superior semicircular canal, where it receives the pretended aqueduct of the vesti- 
bule, with which it then goes into the spungy substance of the posterior part of the 
petrous process and in the mastoid cellules, lined by a prolongation of the dura- 
mater : 2d, another which arises near the centre of the anterior face near the upper 
edge of the petrous portion, and goes behind the superior semicircular canal: 3d 
another which arises at the bottom of the longitudinal fissure which indicates the 
union of the petrous process with the squamous portion of the temporal bone, and 
through which pass some vessels which are distributed in the mastoid cells- and the 
membrane of the tympanum. These details may seem minute, but they are of the 
highest importance, since they contribute to destroy an anatomical error on which 
rests a part of the theory by which physiologists still explain the philosophy of hear- 
ing. F. T. 



or THE EAR. 131 



II. MJSMBBANOUS LABYRINTH. 



§ 1945. The membranous labyrinth(l) is inclosed in the osseous 
labyrinth, and corresponds perfectly to its form, although it is much 
smaller. 

It is formed of a thin and whitish membrane, differing entirely from 
that which covers the inner face of the osseous labyrinth in the early 
periods of fetal existence. Its external face adheres to the inner face 
of the bony labyrinth by a loose cellular tissue. It contains in its cavity 
a fluid called the serum of the membranous labyrinth or the lymph of 
Cotugno, (aquula labyrinthi membranacei) .(2) Numerous vessels are 
distributed in its external face. 

The upper and posterior part of the osseous vestibule is occupied by 
a rounded and oblong membranous sac in which the membranous 
semicircular canals open, which enlarge also in the parts which cor- 
respond to the enlargements of the osseous canals. Before this sac 
we find one which is rounded, perfectly closed, and consequently en- 
tirely separate from the membranous labyrinth, which is smaller, si- 
tuated partly in the semicircular fossa, and also filled with a serous 
fluid. These two sacs are attached to the osseous labyiinth by their 
posterior wall. The anterior, which looks toward the anterior wall of 
this latter and the fenestra ovalis, is loose and surrounded by the serum 
of the osseous labyrinth. The semicircular canals are arranged pre- 
cisely like the osseous semicircular canals. 

The membranous cochlea is formed by a fibrocartilaginous layer, 
the membranous spiral lamina, which is adapted to the external and 
loose edge of the osseous spiral lamina, and which becoming softer 
and thinner on the outside is attached by its external edge to the outer 
side of the osseous cochlea. This lamina is longer than the osseous, 
for it extends to the summit of the cochlea. In this part of its course 
it is loose on its inner edge, while the external is attached as in every 
other part. It terminates in a prominence. 

(1) Scarpa, he. cit.~ Brugnone, Observations anatomico-physiologiques sur le la- 
byrinthe de Voreille; in the Mimoires de Turin, 1805-1808, p. 167-176. 

(2) Ribes (loc. cit., p. 207) remarks that there are many adults in whom this hu- 
mor fills the labyrinth, but there are many in whom it is partially empty, and who 
nevertheless always hear perfectly. He concludes, from these remarks, that the 
labyrinth is not constantly filled by serum, and that then there is in fact a space 
doubtless occupied by an aeriform fluid ; but this space, he adds, does not always 
exist equally in all the cavities of the labyrinth. Sometimes, in fact, we find little of 
this humor in the semicircular canals, and much in the vestibule and the cochlea ; 
and sometimes the semicircular canals are full, while the other cavities contain but 
little. Finally he thinks that these changes depend only on the situation in which 
the cadaver is held. These observations folly confirm those of Brugnone (Mem. 
de Turin, vol. xvi., p. 167), who also thinks that there is almost always serum in all 
the cavities of the labyrinth, but that this liquid does not exactly fill them in the 
natural 6tate, because spaces exist in ice removed from them, although liquids ac- 
quire more volume by congelation. F. T. 



132 DESCRIPTIVE ANATOMY. 



III. AUDITORY NEBVE. 



§ 1946. We have already mentioned the origin of the auditory 
nerve and its course to the internal auditory passage, accompanied by 
the facial nerve. On entering this canal the auditory nerve divides 
into several branches, which enter the labyrinth, and the progress of 
which is indicated by the arrangement of the bones. 

In fact the internal auditory passage(l) presents at the base of its 
cavity forward, in the place where the internal and perforated plate of 
the axis of the cochlea is situated, a crest, the direction of which is from 
before backward ; it is at first slightly sensible, but is very marked in 
the adult, which divides it into two halves, a superior and an inferior, 
which is larger. The first belongs entirely to the facial nerve, while 
the other belongs to it only in a small portion of its anterior part, so 
that we may say that the superior groove receives the facial nerve, and 
the inferior the auditory nerve. The first is divided by a longitudinal 
prominence into two halves, an anterior, the commencement of the 
Fallopian canal, and a posterior, in which the superior branch of the 
auditory nerve is situated. 

§ 1947. The auditory nerve is distributed to the membranous laby- 
rinth. (2) Its first branches go to the semicircular canals and the ves- 
tibule. The first, the largest, passes through the depression behind 
the origin of the Fallopian canal, and arrives at the sac of the superior 
semicircular canal ; the second goes to the oval depression of the ves- 
tibule ; the third, still smaller, arrives at the sac of the posterior semi- 
circular canal. 

When the first branch has arrived thus far it divides into two twigs, 
which separate like a fan ; one of them goes to the larger or common 
sac of the semicircular canals, while the other belongs to those of the 
superior and the external canal. 

All these twigs are evidently fibrous and interlace on the outer face 
of the sacs, but when examined on their inner face they appear to be 
a formless mucus. They do not extend over the whole vestibule and 
the semicircular canals, but remain very distinct upon the surface of 
the sacs. 

The nerve then goes forward in the axis of the cochlea, follows 
exactly the curves of the cavity, and gives off numerous filaments 
which go inward through the openings in its axis. 

The first filaments given off are the largest ; the others gradually 
diminish, and are nearer together. 

Finally the nerve terminates at the summit of the axis by a consi- 
derable filament much larger than the others, and which enters the 
openings in the axis. 

(1) Ribes, he. cit., p. 660. 

(2) Ribes, ibid. p. 665. 



OF THE EAR. 133 

The most internal of these filaments pass through the openings in 
the curves of the pillar, enter into the canals which terminate there, 
arrive on the spiral lamina, form an extremely minute plexus along its 
two faces, and terminate on the membranous spiral lamina, where they 
are entirely exposed. 

Scarpa(l) asserts that they proceed only between the two plates of 
the spiral lamina ; but they in fact cover also the outside of the supe- 
rior and inferior faces of thisjayer,(2) and those seen in this place, par- 
ticularly those on the lower face, are even the largest. Some fewer 
and much smaller filaments pass through the foramina in the spires of 
the cochlea near the pillar, and go not into the spiral lamina, but to 
that portion of the membranous cochlea which forms its external wall. 
All anastomose together on the outside of the cochlea. 

The nervous filaments which enter the cochlea are, like the prece- 
ding, white, opaque, and evidently fibrous near their origin ; but their 
latter expansions are semitransparent, more gray, and similar to 
mucus. 

§ 1948. The changes which are communicated to the cerebrum by 
the auditory nerve and excite there the sensation of sounds, take place 
in the expansions of this nerve in the membranous labyrinth. These 
changes are doubtless caused by the compression which the serum in 
the labyrinth' exercises on the ramifications of the nerves, and this 
pressure is necessarily the consequence of a change in the state of the 
parts on the outside of the labyrinth, especially in the little bones of 
the car and their muscles. In fact, according as the base of the 
stapes is more or less deeply, and partially or wholly imbedded in 
the fenestra ovalis, it compresses the serum within it in different 
degrees, and presses upon different parts of the labyrinth. The 
external ear and the membrane of the tympanum principally serve to 
receive the undulations of sound and to strengthen them, which is 
effected by the tympanum |ind the mastoid cells. In regard to the 
little bones of the ear, independent of the use assigned them, the malleus 
certainly modifies the degree of tension of the membrane of the tym- 
panum, serving to diminish it in loud and to increase it in weak sounds. 
The Eustachian tubes serve to evacuate the fluids secreted in the 
tympanum and to admit the air, to balance that acting on the out- 
side of the membrane of the tympanum. They concur also directly to 
hearing, for they also lead into the tympanum the undulations of sound, 
which, reflected by the walls of this cavity, fall principally on the 
membrane of the fenestra rotunda, called for this reason the accessory 
tympanum.(3) 

(1) De org. and. et olf., p. 55-56, § xi. 

(2) Monro, On the ear, p. 197-199, vol. iii-iv. 

(3) Savart has concluded from his important researches on the mechanism of 
hearing : 1st, that the communication of the vibrations by the air seems to take 
place, at least for small distances, according- u> the same laws as those for solid bo- 
dies; 2d, that it is not necessary to suppose a special mechanism to cause the mem- 
brane of the tympanum to vibrate continually in unison with the bodies which act 

Vol. III. IS 



134 DESCRIPTIVE 4NATOM1 

ARTICLE TH HID 

DIFFERENCES IN THE EAR DEPENDENT UN DEVELOPMENT. 
I. EXTERNAL EAR. 

§ 1949. The external part of the organ of hearing does not begin 
to appear till towards the end of the second month of pregnancy, It 
first resembles a slightly perceptible eminence formed like an elongated 
triangle, the base of which looks upward, the summit downward, and 
which is directly continuous with the lower part of the side of the 
head, and in the middle of which is a triangular longitudinal fissure 
which becomes narrower and deeper from above downward. The 
prominence which surrounds the median depression soon rises to its 
posterior part, and becomes thinner in this place. It projects above the 
surface of the side of the head, and slightly shows the median fossa. 
At the same time, or soon after, the anterior part of the prominence is 
divided by a transverse fissure which arises from its posterior part into 
two halves, of which the inferior is the antitragus and the superior the 
commencement of the helix. At the same time this anterior part of 
the external ear also rises and the posterior enlarges, but is not rc- 

upon it, and that it is always in the conditions fit to be influenced by any uumbei 
of vibrations ; 3d, that its tension probably does not vary, except to increase or 
diminish the extent of these variations, as Bichat had asserted, but always supposing, 
as Meckel still admits, the contrary of what results from these experiments, that is, 
by imagining that the membrane is loose in loud and tense in lecble sounds ; 4tli, 
that the vibrations of the membrane extend to the labyrinth unchanged by means 
of the little bones; 5th, that the little bones also serve to modify the extent 
of the vibrations of the parts in the labyrinth; 6th, finally that the tympanum pro- 
bably serves to contain an air the physical properties of which arc constant. It, ml 
asserts that the membrane of the tympanum does not perform any motion which 
is visible or denoted by a bristle situated in the centre; but the more delicate 
experiments of Savart do not allow us to doubt these motions. When we saw the 
temporal bone on the level of the external face of the membrane, and cover this with 
sand, we can perceive that the grains move slightly when we bring a disquc which 
is vibrating, parallel to the membrane and near the surface, although its slight extent 
and especially its form do not allow us to establish there any nodal line. Itard 
states that the function of the little bones, are to allow us to hear low tones. J. P. St . 
Hilaire thinks that they are of but little use, and arc only indications of the respira- 
tory apparatus, the operculum, developed in fishes. The justice of this second pro- 
position, which we shall not examine here, would not necessarily involve that of the 
first, although not contradicted by experience. The direct participation of the 
Eustachian tube in hearing, which was asserted in the commencement of the I;, si 
century, and afterwards brought forward by Bressa, is evidently erroneous. It lias 
been perfectly refuted by Cotugno and Itard. If it was correct, we ought, as Ru- 
dolphi asserts, hear our own voice when speaking loudly after stoppii 
but this is not true. Itard has very ingeniously compared the Eustachian tube to a 
hole without which the air in a military drum would nol vibrate ; bui he is mistaken 
in saying that it seems only to renew t lie air in the tympanum. This is undoubtedly 
its principal function, but it also si il, nsci 

perspiration constantly secreted by the mucous! membrane of this cavity. F. T. 



OF THE EAR 135 

moved farther from the side of the head. The anthelix and the tragus 
are developed also very early at the third month. The anthelix is at 
first more prominent than it is subsequently, because the posterior 
edge of the ear rises but slightly or not at all. The lobule appears 
last. 

The external ear is much smaller in proportion to the head, the 
younger the fetus is. 

Its cartilage begins to appear at the third month ; but it is deve- 
loped slowly, for towards the end of pregnancy it is not as yet so 
extensive under the skin as in full grown individuals. 

The cartilaginous portion of the auditory passage, like the external 
ear, is at first proportionally much smaller than subsequently. 

The long portion of this passage begins to form some time after birth 
by the enlargement of the cavity of the tympanum. Its ossification is 
singular in this respect, that it generally begins much sooner in the 
external part of the canal, where it unites to the cartilaginous portion, 
than in the middle region of its lower part. 

The prolongation of the external cutaneous system, around which 
this passage is situated, already exists very early in the fetus, and 
it is not then even proportionally much shorter than in the adult, 
but it has another form and another direction. As the direction of the 
tympanum is then much more oblique from without inward than it 
is afterward, the upper part of its circumference at first does not 
exist ; the inferior alone is developed, and forms on the outside and at 
the bottom of the tympanum, a large sac, which is much more ample 
in proportion to its length than it is afterward, descends also more per- 
pendicularly, and is situated below the membrane of the tympanum, 
so as really to form its upper wall. 

The skin of the bony portion of the auditory passage is softer and 
thicker in the fetus than in the adult. 



H. INTERNAL EAR. 

§ 1950. 1st. The tympanum in the early periods of life is proportion- 
ally shorter and narrower than at a later season, particularly, because 
the mastoid process is veiy small, and its cells are not yet formed. It is 
filled in the fetus with a thick gelatinous fluid, and it communicates 
with the mouth more directly the younger the fetus is, since the 
Eustachian tube is shorter and broader in the same proportion. The 
cartilaginous portion of this tube, until the middle of pregnancy, is 
simply membranous, and even in the full grown fetus the bony portion 
i* at most separated within the canal by a layer of bone, which forma- 
tion continues most generally through life, so that the septum rarely 
extends also to the outer si. lo. 

The tympanum, and with it the membrane, arc much larger in pro- 
portion either to the external ear or to the whole head and body, the 
younger the fetus is, and even until the fifth month of pregnancy, both 



136 DESCRIPTIVE ANATOMY. 

are larger than the external ear. Besides, as the osseous portion of 
the auditory passage is not yet developed, the membrane of the tym- 
panum is much nearer the surface in the early periods of existence 
than subsequently, so that the upper part directly touches the entrance 
of the cartilaginous portion of the auditory passage, and consequently 
is almost exposed in this point, a very curious circumstance from its ana- 
logy with reptiles. Both also differ at first in direction, which is more 
horizontal, because at this period the membrane of 1 lie tympanum is 
more oblique from above downward and from without inward. 

2d. The small bones of the car differ from all other bones of the body 
by their uncommonly early appearance and development. 

They are visible and even uncommonly large in proportion, at the 
commencement of the third month of pregnancy, although at this 
period they are still entirely cartilaginous, ami wc cannot well dis- 
tinguish the stapes from the incus. Thus, for instance, the malleus is 
about three lines high in the fetus of four months, so that the body 
being then four inches from the vertex to the coccyx, its length 
is to that of the whole body as 1 : 16, while in the adult, where is to 
four lines long, and where the distance between the vertex and the 
coccyx is two feet and a half, the proportion is only as 1 : 90. The 
small bones of the car are as large in the full grown fetus as in the 
adult. 

They begin to ossify also very early, even before the end of the third 
month. Cassebohm asserts(l) that the stapes and incus ossify sooner 
than the malleus, that the osseous nucleus of the incus is seen first in 
its anterior branch, and that of the stapes in the head, whence it ex- 
tends along the two branches to the base, which, with the lower region 
of the anterior branch, ossifies the last. In the malleus, ossification 
commences in the head and anterior process. Our observations do not 
exactly agree with those of Cassebohm. Tt is true that the anterior 
branch of the incus ossifies before the posterior : we have always found 
it perfectly ossified, while the latter was entirely cartilaginous, but the 
ossification of the malleus commences at the same time as that of the 
incus, and the stapes is still entirely cartilaginous, when it has ad- 
vanced considerably in the other two bones. The place where it be- 
gins in the stapes is not well determined : it is sometimes in the lower 
part of the posterior branch, and sometimes in the base, but never, ac- 
cording to our observations, in the head. 

These bones differ very much in their forms. The incus changes 
the least. The branches of the stapes seem at first not to be separated 
from each other, which deserves to be noticed on account of the ana- 
logy resulting from it with the formation of this bone in the cetaceous 
animals, and with that of the inner part of the single bone of the ear 
in birds and reptiles. It is certain that even where these two branches 
are detached from each other, the opening between them and the base 
is proportionally much smaller than at ut periods, although, 

(1) Loc. cU. t p. 56. 



OF THE EAR. 137 

however, its form is then less oblong. This narrowness of the fora- 
men, which is evidently an approximation to its entire deficiency, and 
the union of all the parts of the stapes in one, depend principally on 
the greater thickness of its branches. 

But of all the bones of the ear, the malleus changes the most during 
its development. Perhaps no other bone can be compared with it in 
this respect. 

The most remarkable difference is the existence of a right cartila- 
ginous process, formed like a very elongated cone, which is also very 
long and very thick in proportion to the rest of the bone. This pro- 
cess arises from the anterior side of its head, leaves the tympanum 
between the petrous process of the temporal bone and the ring of the 
tympanum, is fitted directly to the inner face of the lower jaw, and 
extends to the anterior extremity of this bone, where it sometimes, 
perhaps even always, unites with that of the opposite side. This 
cartilage never ossifies, although in the commencement it forms most 
of the mass of the bone ; it disappears at the eighth month. The an- 
terior process of the malleus corresponds with it, it is true, to a certain 
extent, in respect to its position : but we also perceive that in the fetus, 
where the two parts are distinct from each other, the cartilage is situ- 
ated above the anterior process. We may then at most admit that this 
latter makes part of it, and that they are separated very early. This 
cartilage is very curious, because fishes, reptiles, and birds, present a 
similar one, which extends from the posterior to the anterior portion of 
the lower jaw. In these animals it rests on a small bone placed on 
the inner face of the posterior part of the lower maxillary bone, and we 
may consider it as a rudiment of the malleus, which does not exist in 
them. 

3d. The membranous labyrinth exists long before the osseous 
labyrinth. We have found it at three months perfectly developed in 
the cartilaginous mass, which afterwards ossifies. Even in the early 
periods of life it is more distinct, and formed of firmer and more solid 
membranes than at subsequent periods. It is composed at first of two 
very distinct membranes, an external and an internal, which are 
simply inclosed in each other, but there is no continuity between 
them. 

The internal is white, transparent, thinner, but firmer and more 
elastic than the external. The latter does not adhere to the cartilage, 
as afterward it is not attached to the bone which is developed at the 
expense of this latter. 

The inner face of the external membrane is smooth, and the external 
is corrugated. It gradually disappears, so that at seven months we 
cannot trace it. Before entirely disappearing it gradually becomes 
thinner. The internal becomes proportionally narrower but firmer : it 
seems to be attached more intimately to the inner face of the cartilage 
which surrounds it, in the early periods of existence than subse- 
quently. 



138 DESCRIPTIVE ANYT' 

As yet we have been unable to ascertain if there is not a period 
when the membranous labyrinth is uncovered in the skull, at least in 
part, and where its structure is more simple than it is afterward. At 
three months it is entirely surrounded by a mass of cartilage, and is as 
complex in its structure as at a more advanced period of life. We only 
remark, that like the cartilage which envelops it, it is at first more 
compressed from without inward, and proportionally higher, winch un- 
doubtedly depends, at least in part, on the greater development of the 
encephalon. . . 

At four months we find the membranous cochlea as complex as it is 
in the adult, while afterward its circumference seems to be formed only 
by the membranous labyrinth; it is then constituted by a very thick 
membrane, which makes a part of this latter. We have as yet been 
unable to obtain any sufficient data in regard to its form before the 
fourth month of pregnancy. 

The secondary tympanum and the fincstra rotunda are at first 
situated more externally and parallel to the membrane of the tympa- 
num. They afterwards go backward, which depends principally on 
the development of bone in their circumference. 

4th. When we study the development of the osseous labyrinth, we 
must distinguish the formation of the osseous substance of the petrous 
process of the temporal bone from that of its own. The first commen- 
ces before the second, and follows the usual mode of ossification, 
that is, it takes place by the development of a loose, soft, and plexi- 
form tissue, in the homogeneous mass of cartilage previously existing, 
which gradually extends from before backward. The circumference of 
the fenestra rotunda ossifies first towards the end of the third month, 
which is curious as an analogy between this opening and the tympa- 
num. Ossification begins at the upper part, then extends to the lower, 
and when it has thus formed a ring, it goes forward. At the same 
time there is developed a special osseous nucleus, which is entirely 
distinct from the preceding, at the outer extremity of the superior per- 
pendicular semicanal : next there appears a third small scale at about 
the centre of the internal perpendicular semicanal. At the same time 
ossification proceeds rapidly backward and downward from the point 
first formed, and gives rise to the floor of the labyrinth. The second 
nucleus enlarges more quickly perhaps than the first, so that the su- 
perior perpendicular semicanal is soon entirely ossified, excepting only 
its lower and concave face. At the same time, ossification, commencing 
at its internal extremity, advances on the internal face of the petrous 
process, circumscribes the internal auditory foramen, enters within it, 
and forms the floor of the cochlea. 

The horizontal semicircular canal begins to ossify at the fifth month. 
At this time the piece of bone which forms the superior perpendicular 
canal extends backward, downward, and outward, around the mem- 
branous horizontal canal. At least we have been unable to discover 
a special nucleus for this canal, which seems to ossify by the extension 
of the first two nuclei, the edges of which finally unite. 



OF THE EAR. 139 

The formation of the interior of the cochlea belongs almost wholly 
to the osseous labyrinth. The cartilage and then the osseous sub- 
stance of the petrous process, do not participate in it except by a nar- 
row prolongation sent by this latter into the cavity containing the 
membranous and then the osseous labyrinth, the spires of which it 
slightly separates. 

The loose edge of this projecting lamina is turned outward. It ex- 
tends from the upper part of the fenestra rotunda and the outside of the 
cochlea, to the summit of this latter, across its cavities, and thus divides 
it anteriorly, but very imperfectly, into an external and an internal 
cavity. This lamina is broader at first than it is subsequently. Be- 
sides, the internal face of the cochlea is entirely smooth, and this part 
of the internal ear presents at this period the greatest analogy with the 
cochlea of birds : at a later period, after the third month, as the cochlea 
enlarges from without inward, the lamina in question becomes nar- 
rower, and at the same time slight prominences are developed, which 
separate externally the two and half turns of the cochlea from each 
other, and make part of it. 

The osseous labyrinth is at first entirely separated from the osseous 
mass of the petrous process which surrounds it, and which is developed 
before it. It is, however, always applied to it. Its surface then is en- 
tirely smooth. The inner face of the osseous mass of the petrous pro- 
cess is also smooth to a certain extent, although more corrugated than 
that of the labyrinth. The two surfaces soon blend together, but they 
can be entirely separated in children, and the smooth polished surface 
of the labyrinth can be demonstrated ; but they afterward become in- 
separable. The line of demarkation is very evident in every part, 
particularly in the cochlea, where it is perceived that the prolongations 
described above are perfectly distinct from the canal formed by the 
membranous and osseous labyrinths. 

Thus the osseous labyrinth is developed independent of the osseous 
substance of the petrous portion. As the external membrane of the 
membranous labyrinth disappears at the period of its formation, it is 
not improbable that it changes into osseous substance, or at least that 
this substance transudes through its external face. In fact, this 
membrane does not exist for some time with the osseous labyrinth, and 
may always be easily separated from it : but we are satisfied, from nu- 
merous observations, that as the osseous labyrinth is developed around 
it, it becomes denser, firmer, dryer, and in a measure horny : hence we 
have been induced to believe that the two modes of formation coexist, 
that is, that the membrane secretes first the labyrinth, then that an 
analogous substance being deposited with it, it unites with the layer it 
had first formed, and becomes i(s internal layer. The formation of the 
osseous labyrinth would thus resemble that of the teeth. (1) 

(1) Ribes has asserted that in the fetus the serum of the labyrinth is reddish, 
bloody, and exactly fills it. As the infant grow* older, it Ix-vomes clear, limpid, and 
less in quantity, and the cur becomes more sensible to sounds. P. T. 



140 DESCRIPTIVE ANATOMY. 

ARTICLE FOURTH. 

ORGAN OF HEARING IN THE'ABNORMAL STATE. 

§ 1951. As the organ of hearing is very complex, it presents very 
numerous and very different anomalies(l) in respect to their essence ; 
by these the ear is unusually hard or soft, or is entirely deficient. 

§ 1952. The deviations of formation are here, as in every other part, 
the most interesting in a physiological point of view. 

As in all other parts of the body, they are more or less characterized 
by a retarded development, (2) and are also more or less repetitions of 
what is observed in animals inferior to man. 

Sometimes the development of the whole ear is arrested. (3) 

I. EXTERNAL EAR. 

§ 1953. 1st. Deviations of form in regard to quantity. The entire 
absence of the external ear, of which we possess some instances, de- 
pends on the permanence of a state which marks the early periods 
of fetal existence. 

The anomaly varies a little less from perfect development when the 
ear is closed, which can exist in different degrees ; these lead imper- 
ceptibly to the normal formation by the shortness and narrowness of 
the external auditory passage. 

The absence of the lobule, or its adhesion with the skin of the head, 
is the least deviation from the normal state. This state also exists 
regularly at a certain period of the formation of the fetus. 

We may consider the frequent enormous enlargement of the ears as 
an anomaly of an entirely different character. 

2d. Deviations of formation in regard to quality. These are the 
turning of the ear on the orifice of the external auditory passage, 
which more or less closes this canal. (4) 

II. INTERNAL EAR. 
A. TYMPANUM. 

§1954. 1st. Deviations of formation in respect to quantity. Some- 
times the tympanum is not sufficiently large, and is even closed on the 

(1) Beside3 the works of Duvernoy, Wildberg-, and Saunders, already mentioned, 
which treat also of the diseases of the ear, consult, J. A Rivinus, De auditus vitiis, 
Lcipsic, 1717.— J. M. G. Itard, Traite" des maladies de Vorcillc el dc Vaudition, 
Paris, 1821.— C. F. A. Eschke, Diss, de auditus vitiis, Berlin, 1819. 

(2) See on this subject our Handbuch dcr patlwlogischen Anatomic, vol. i. P- 
400-406. 

(3) Rcederer, Descript. fceiusparasit.; in Coram, soc. Geetl., vol. iv. 

(4) Walter, Fetthautgeschwulste, Landshut, 1814. p. 33. 



OF THE EAR. 141 

outside as in fishes. Sometimes one or more of the little bones of the 
ear are deficient, or they are too small.(l) Sometimes they are un- 
usually large, thus preserving the distinctive characters of the fetus. 
They are rarely more numerous than usual. When supernumerary 
bones exist, they are always very small. They occur particularly be- 
tween the malleus and incus, and also in the neck of the stapes. 

2d. Deviations of formation in regard to quality. The bones of the 
ear are sometimes formed after a different type, and then are more or 
less similar to those of certain animals. 

Thus Comparetti(2) observed in a man, that not only the two 
stapedes were very small, but also formed by a single branch, with a 
small base closing the fenestra ovalis, which was very narrow. (3) 

' B. LABYRINTH. 

When the labyrinth is very imperfectly developed, there is only a 
single cavity closed externally, which is not divided into the vestibule, 
cochlea, and semicircular canals, and which does not communicate 
with the tympanum. (4) This form resembles that of the organ of 
heaving in the Crustacea and the cephalopoda. Perhaps it is normal 
also in the early periods of the existence of the human fetus. 

When the development is more advanced, the cochlea describes 
fewer turns than usual, (5) even as in reptiles and birds, it appears as 
a sac-like prolongation, which is not curved on itself. From our pre- 
ceding remarks, this anomaly should be considered as a continuance 
in the fetal state. 

The labyrinth is sometimes ossified imperfectly, whence a portion of 
the membranous labyrinth is exposed. (6) 

(1) Bernard, Sur un vice d> organisation de Vorcillc externe ; in the Journ. de 
■pkysiol. exper., vol. iv. p. 167. 

(2) Loc. cil., p. 24. 

(3) We find the malleus sometimes larger, sometimes shorter, sometimes with an 
enlarged head or process. The incus has heen observed sometimes narrower, some- 
times broader, and sometimes with it* long branch more or less arched. Rudolphi 

icribed and figured (J)iss. &is. observationes osteologicas, Berlin, 1BJ2, tab. i. 
fig. If).) a stapes, of which the branch alone communicated with tlie base, the other 
being loose, and forming with the preceding an obtuse ang-le. Lreseckc seems to 
have observed a similar case (Obs. anat. chirurg., Berlin, 1754, p. 15.) Tiedemann 
has described a stapes found in a newly born infant, which presented neither 
branches nor opening. It resembled a small pyramid, the base of which represented 
the plane surface, and from whence a piece of bone arose, slightly depressed, which 
was articulated with the long branch of the incus by a rounded process. He has also 
seen in an adult the two branches of the stapes completely united by a layer of bone, 
so that there is a slight depression, but no opening between them (Sur quclqucs 
variations- dans la for tnc dc V drier chcz Vhommc ; in the Jo urn. complcm. des sc. 
mid., vol. viii. p. S3. P. T. 

(4) Rodcrcr, loc. cit.— Meckel, Handbuch dcr pathologischcn Anatomic, vol. i. p. 
406. 

(5) Mondini. Anal, surdi nail; in the Comm. Bonon., vol. viii.— Meckel, loc. cit. 
vol. i. p. 403. 

(6) Mondini, luc. cit. 

Vol. III. 19 



142 DESCRIPTIVE ANATOMY. 



C. AUDITORY NERVE. 

Sometimes in deaf and dumb people the auditory nerve is smaller(l) 
by half than it is generally. (2) 

§ 1955. The accidental or consecutive deviations of formation result 
from an external lesion, which is purely mechanical, or an alteration in 
texture. Sometimes in hydrocephalus the two external bones oi the 
ear are pushed outward and detached from the stapes, and sometimes 
even this is unconnected with the fenestra ovalis.(3) 

§ 1956. The alterations of texture in the organ of hearing are prin- 
cipally inflammation and its consequences, among which we must first 
mention adhesion and suppuration, which frequently affect the ex- 
ternal and the internal ear. The buccal orifice of the Eustachian 
tube is frequently obliterated after scarlatina, or the tympanum 
and the bones are destroyed by ulceration. The entire or partial de- 
struction of the membrane of the tympanum and very probably also 
the anomalies in the tumors of the labyrinth, which are thickened,(4) 
solidified, and changed into a hard body (5) after long affections of the 
internal ear,(6) belong to this class. 

The new formations developed in the organ of hearing are : 
1st. Accidental ossification, by which the bones of the ear adhere to 
each other, and obstruct the fenestra rotunda,(7) in which case we also 
find the bones, particularly the stapes, twice as large as they are gene- 
rally : the stapes also is fused with the fenestra ovalis,(8) and forms 
osseous concretions (9) in the membrane of the tympanum. (10) 

(1) Haighton, Mem. of the med. society, vol. iii. p. 1. 

(2) This fact has been observed several times, among - others by Sylvius, Hoffman, 
and Arenda. Itard also has seen it: but he thinks that the wasting- of the auditory 
nerve is more frequently the effect than the cause of deafness (loc. cit., vol. i. p. ^92.) 

(3) Blumenbach, Gcschichte der Knochen, p. 140. 

(4) Haighton, loc. cit. — Cline, in Saunders, loc. cit., p. 88. 

(5 ) Seeon this subject an important memoir on the physiological relations, by G. 
P. St. Hilaire, Sur la nature, la formation et les usages des yierres qu'un trouve 
dans les cellules auditives des poissons ; in the Mem. du Museum, 1824. 

(6) Itard has seen one case {loc. cit., vol. i, p. 395) where the fluid of the labyrinth 
was deficient. 

(7) Cotugno, loc. cit., § 72, p. 61. 

(8) Valsalva, De aure humand, cap. ii. § x. 

(9) Cassebohm, vol. iii., p. 33. — Loesecke, Obs. anat., p. 25. — Koehler, Beschrei- 
bung der Loderischen Prdparatc, p. 148. 

(10) Ribes {loc. cit., p. 654) has found the membrane of the fenestra rotunda ossified 
in a man completely deaf, and destroyed in several subjects, some of whom had not 
completely lost the power of hearing. This latter circumstance deserves to be re- 
marked, since complete deafness does not result from injuries of the membrane of 
the tympanum, which is so analogous to that of the fenestra rotunda. According 
to Piuel's observations, it would seem that deafness depends on an alteration in the 
texture of the mucous membrane of the internal ear rather than on any other cause, 
although he seems to attribute it to the diminution of the fluid in the labyrinth, 
which in this case is only a consequence of inflammation. (Kechcrchi s sur les 
causes de la surdite chez les vicllards ; in the Archie, gen. dc mid., vol. vi., p. 247.) 

F.T. 



OF THE EYE. 143 



2d. The formation of accidental cartilages and nbro-cartilages some- 
times observed under the form of tumors which adhere to the auditory 
nerve.(l) 

Among the entirely abnormal formations we must arrange the 
fungous tumors and the polypi, which are developed principally in the 
mucous membrane of the auditory passage. 



CHAPTER II. 



ORGAN OF SIGHT. 



§ 1957. The organ of sight (oculus)(2) occupies the upper part of 
t)]e front of the face, and is situated on the right and left, on the sides 
and above the root of the nose in the orbit and circumference of this 
cavity. We distinguish the eye or the globeof the eye (bulbus oculi) 
with the muscles which mt.ve it and the parts which protect it. 



ARTICLE FIRST. 



PARTS WHICH PROTECT THE EYE. 

§ 1958. The parts which protect the eye(3) comprise two folds of 
skin, called the eyelids, very thick hairs, called the eyebrows, and the 
lachrymal passages. 



(1) Sandifort, Obs. anat. pathol., booki. c. 9. 

(2) Fabricius d'Aquapendente, De visione, voce ct auditu, Venice, 1606. — V. F. 
Plemp, Ophthalmographia, s. tractatio de oculo, Louvain, 1648. — G. Briggs, Oph- 
thalmographia, seu oculi ejusque partiwn descriptio anatomica, London, 1685. — J. 
Taylor, Nouveau traite d'anatomie du globe de Vail, avec I'usage de ses differentes 
parlies, et de celles qui lui sont contigues, Paris, 1738. — A. Bertrandi, Diss. II. de 
hepate et oculo, Turin, 1748. — J. G. Zinn, Descriptio anatomica oculi humani, Got- 
tingen, 1753.— G. Porterfield, Treatise on the eyes, the manner and phenomena of 
vision, Edinburgh, 1759. — M. Horrebow, De oculo humano ejusque morbis, Copen- 
hagen, 1792. — A. Monro, Miscellaneous observations on the structure and the func- 
tion of the eyes ; in his Treatise on the brain, the eye, and the ear, Edinburgh, 1797. 
— S. T. Scemmerring, in Demours, TraiU des maladies des yeux, vol. iv. — J. G. 
G. Voit, Oculi humani anatomia et pathologia, Nuremberg, 1810. — C. H. T. Schre- 
ger, Verstich ciner vergleichenden Anatomie des Auges, Leipsic, 1818. — D. G. Scem- 
merring', De oculorum humani animaliumque sectione horizontals, Gottingen, 1818. 
— J. A. Hegar, Diss, de oculi partibus quibusdam, Gottingen, 1818. — C. F. Simon- 
son, Anatomico-physiologicus traclatus de oculo, Copenhagen, 1820. 

(3) Rosenmuller, Organorum lacrymalium partiumque oculi externarum descriptio, 
Leipsic, 1797. 



144 DESCRIPTIVE ANATOMY. 



I. EYELIDS. 

§ 1959. The exjelids (palpebral) are perpendicular folds situated 
before the anterior orifice of the orbit, which they close more or less 
perfectly. They are distinguished into tipper and lower. They blend 
together in the great or internal angle, and the small or external angle 
of the eye (canthi oculi, interims et externus), and are separated from 
each other their entire breadth by a transverse fissure (Jissura palpe- 
brarum). 

The superior is much greater than the inferior ; a flat ligament 
formed of transverse fibres several lines long, leaves the great angle of 
the eye and goes inward between the fibres of the internal portion of 
the orbicularis palpebrarum muscle ; its internal extremity is broader 
than the external, and is attached to the upper part of the nasal p.\$- 
cess of the superior maxillary bone. This is the palpebral ligament 
(lig. palpebrarum). 

The exjelids are composed of two layers ff skin, one external and the 
other internal, of cartilage and muscular fibres. They rarely or never 
contain fat. 

The exterior layer of skin makes a part of the external cutaneous 
system. It differs from the rest of the skin only in being very thin and 
destitute of hair. 

It is continuous on the edge of the eyelids, which is nearly a line 
broad, with the internal layer which belongs to the internal cutaneous 
system, that is, to the mucous membranes. This layer is also thin, 
reddish, and moist. 

It is termed the' conjunctiva. It lines the whole extent of the inner 
face of the eyelids, is reflected on itself in the parts where these movable 
folds' are attached to the rest of the skin, and is called the tunica ad- 
nata, is fitted to the anterior part of the sclerotica, from which it may 
always be easily separated, and which it covers to the circumfi 
of the transparent cornea. At least it is not possible strictly toil. 
stiate that it extends also on the anterior face of this last membrane, 
for if in certain morbid affections a layer rises on the anterior face of 
of the cornea, this circumstance authorizes us to think, but does not 
prove, that this layer in question is a prolongation of the conjunctiva. 
Admitting that this passes really on the cornea, and that it blends with 
the external pellicle of this membrane without any marks of se] 
tion, it does not follow that it possesses in this place the cha I 
serous membranc,(l) for the anterior face of the transparent ci 
belongs rather to the class of the mucous membranes. (2) Walthi 
already demonstrated(3) that it is wrong to exclude the conjunctiva 

(t) P. F. Walther, Abhandlungcn aus dem Gcbicie dcr praklischcn Med Laod- 
shut, 1810, p. 413. 
(2^ Wardrop, Morbid anatomy of the eye, Edinburgh, 1818, p. 14. 
(3) Loc. cit., p. 414. 



OP THE EYE. 145 

entirely from among the last membranes. The adhesions(l) between 
its two opposite faces which have been brought forward to sepa- 
rate it from the other mucous membranes, and which have been used 
to a certain extent to class it among the serous membranes, are rare 
and accidental, and supervene probably after suppuration, in which 
case even the mucous membranes contract adhesions. 

A. EYELASHES. 

§ 1960. The anterior part of the edges of the eyelids presents three 
or four irregular ranges of short, straight and arched hairs, which gra- 
dually become larger from the two angles of the eye to the centre, and 
which are termed the eyelashes (cilia). (2) Those of the upper lid are 
more numerous and stronger than those of the lower. The former 
are arched from above downward, the latter from below upward. 
When the lids close they intercross and form from their curve a broad 
ridge. 

D. MEIBOMIAN GLANDS. 

§ 1961. Farther back and nearer the posterior limit of the edge of 
the eyelids, at about its centre, is a series of openings regularly arranged, 
which are also larger in the upper than in the lower eyelid, and 
which do not occupy the entire breadth of these movable lids. These 
openings lead to the glands of JWeibomius, or the sebaceous glands of 
ike eyelids (Gl. JWcibomianoz, s. 'palpebrarum sebaceae), small, very 
elongated, narrow, tortuous bursas, which terminate in sacs generally 
single, but sometimes divided at their base into several compartments, 
which are situated perpendicularly below the conjunctiva, between it 
and the tarsal cartilages. These glands are filled with a thick, yel- 
lowish viscous substance, called tema, which accumulates around the 
-lies during sleep, and which is easily distinguished by its color 
from the red conjunctiva. 

C. PALPEBRAL CARTILAGES. 

§ 1962. Each eyelid contains between the two layers of skin and 
near its loose edge an oblong cartilage, called the tarsus, which de 

ncs its form. These cartilages extend much farther from \i ithout 
inward than from above downward, and they arc very thin from before 

ward. They are much thicker at their loose and straight edge 
than on thch convex portion, which looks to the base of the eyelids ; 

Schmidt., in the Ophthalmofogischc Bibliothefc., vol. in., part 1, p. 18. 
(2) H. Meibom, De vasis palpebrarum novis Epist., Helmstadt, 1666, 



146 DESCRIPTIVE ANATOMY. 

they extend on the inside only to the lachrymal puncta, and terminate 
on the outside also a little before the commissure of the two eyelids. 
Their convex edge and their internal and external extremity becomes 
at the two angles of the eye a very dense cellular tissue, which is 
called the tarsal ligament (lig. tarsi, internum et externum) ; this unites 
them to the external and internal edge of the anterior opening of the 
orbit. 

D. MTJSCLES OP THE EYELIDS. 

§ 1963. The eyelids have two muscles which act in opposite di- 
rections, the orbicularis palpebrarum and the levator palpebroz supe- 
riors muscles. The first is common to the two ; the second be- 
longs to the upper eyelid only. The lower eyelid has no special 
muscle. 

A. ORBICULARIS PALPEBRARUM MUSCLE. 

§ 1964. The orbicularis palpebrarum muscle, naso-palptbral, Ch. 
(JVf. sphincter palpebrarum, s. oculi), is thin, membranous and circular, 
although a little elongated. It occupies the upper and anterior part 
of the face and the lower and anterior part of the skull. Consequently 
it is not by any means confined solely in the ej^elids. 

Its internal part is the slightest but the thickest. After leaving this 
point it extends considerably upward, downward and outward. 

It is attached above and below to the palpebral ligament, so that it 
may be said to leave the inner angle of the eye and to return to it. 

Besides this origin, several other fasciculi pass before and behind 
the palpebral ligament, whence it follows that a portion of this muscle 
is formed by uninterrupted circular fibres. 

The orbicularis muscle arises above by short tendinous fibres from 
the upper extremity of the nasal process of the superior maxillary 
bone, from the os unguis, and the lower and anterior part of the nasal 
and orbitar portions of the frontal bone. 

It arises below by similar fibres from the lower part of the inner 
edge, and from the inner part of the lower edge of the orbit, which are 
formed by the ascending process and by the body of the superior max- 
illary bone. 

Its fibres separate especially in its lower part, and fasciculi are de- 
tached from its outer part, some of which go the cellular substance 
and others enter the zygomaticus minor and the levator labii superioris 
muscles. 

The internal part of this muscle which is contained in the eyelids, 
where it is situated directly below the external cutaneous layer, is 
much less extensive than the external. Its fibres are straighter, 
thinner and paler than those of the latter, with which it is always un- 



OF THE EYE. 147 

interruptedly continuous, although it has been considered a special 
muscle, called the ciliaris muscle. 

B. LEVATOB PALPEBBJE SUPEBIOBIS MUSCLE. 

§ 1965. The levator palpebral superioris muscle, orbito-palptbral, 
Ch., is very long, thin and triangular. It arises by a short tendon at 
the base of the orbit from the periosteum which lines the upper part 
of the optic foramen, and blends in this place with the tendons of the 
rectus internus and rectus superior muscles. It gradually becomes 
broader and thinner, advances directly under the orbitar plate, covering 
first the inner and then the whole of the rectus superior muscle. It 
finally becomes a very thin tendinous expansion, often scarcely per- 
ceptible, part of which is attached to the upper edge of the superior 
palpebral cartilage, while the other passes between the orbicularis 
palpebrarum muscle and this cartilage, and extends to its lower edge 
where it is inserted. 

It raises the upper eyelid. 

E. THIRD EYELID AND CARUNCULA LACHRYMALIS. 

§ I960. Beside the upper and lower eyelids there is also in the 
great angle of the eye a third which is much smaller and imperfect. 

The two palpebral commissures differ in form. The external is 
more pointed than the internal. The latter resembles a small and 
narrow prolongation of the palpebral fissure towards the nose, the 
separation of which with the rest of the fissure is marked very evi- 
dently by the lachrymal puncta, and which terminates inward in a 
rounded edge. 

The third eyelid is found in this space. 

It has the form of a triangle, the summit of which looks inward and 
the loose edge outward ; this last is semicircular. It is formed by a 
fold of the conjunctiva by a small palpebral cartilage situated near its 
loose edge, and by a considerable number of sebaceous glands united 
in a rounded or slightly triangular mass, between which are small, 
straight and very fine hairs analogous to the eyelashes. 

The sebaceous glands are situated entirely inward, and project par- 
ticularly on its anterior face. 

They are called the caruncula lachrymalis. The external and loose 
part of the third eyelid which passes much farther forward than the 
caruncula, has been termed the semilunar fold (plica semi-lunaris) . 

This part then really possesses all the constituent parts of an eyelid. 
It differs from the other eyelids by its smallness and in the deficiency 
of an external layer of skin and of muscular fibres. It is in fact a 
rudiment of the third eyelid which exists in most vertebrated animals. 
In fact the perpendicular eyelid of these last differs from it only by its 



148 DESCRIPTIVE ANATOMY 

greater size. When we descend in the animal scale we sec that its 
development is always in an inverse ratio with that of the horizontal 
eyelids, and that finally it entirely replaces them. 

II. EYEBROWS. 

§ 1967. The eyebroius (supercilia) are short, strong, compact hairs, 
which gradually increase in size from within outward, and which are 
arranged in several superimposed stria?. These hairs form a Utile 
above the upper eyelid an arch, the convexity of which looks upward. 
The two arches they describe blend more or less at their inner part. 

We may consider this part of the face as the commencement of the 
upper eyelid. 

The eyebrows are moved each by a special muscle, the corrugator 
supercilii. 

The corrugator supercilii muscle (fronto sourcilier, Ch.) is thick 
and large. It covers the inner part of the upper edge of the orbit. It 
is covered at its origin by the upper internal part of the orbicularis pal- 
pebrarum muscle, and by the internal and inferior part of the frontalis 
muscle ; it arises by very short tendinous fibres from the frontal bone, 
below the inner part of the supraciliary ridge. Its fibres are oblique. 
Its direction is outward, and it gradually becomes thinner. It is so 
blended, particularly in its external part, with the upper portion of the 
orbicularis palpebrarum muscle, which entirely covers it, and which 
may be considered as a deeper layer of this latter muscle. 

It wrinkles the eyebrows, and the skin of the forehead perpendicu- 
larly. 

III. LACHRYMAL PASSAGES. 

§ 1968. The lachrymal organs ox passages (organa lachrymalia, s. 
vuc lachrymalcs), form a special apparatus, the function of which is to 
secrete and excrete a transparent liquid termed the tears (lachryma).(\) 

This apparatus includes the lachrymal gland and its excretory ducts, 
the lachrymal puncta, and the lachrymal passages, the lachrymal sac, 
and the nasal canal We may annex to a certain extent the con- 
junctiva, as it is uninterruptedly continuous with the excretory 

b, the gland, and the lachrymal puncta, and as, strictly speak- 
ing, it is only a considerable dilatation of the excretory portion of the 
lachrymal organ. 

A. LACHRYMAL GLAND. 

§ 1969. Only one lachrymal gland is commonly admitted :(2) there 
arc, however, two, generally arranged so that one is superior, the other 

(1) Rerzclins, i>. A. ii. p. 219-221. 

(2) N. Stcnon, Di oculorum i 

tomicwquibus venlacrymatumf antes dctcgunlur ; in the Obs. anal., Lcydcn, 1GC2. — 



OF THE EYE. 



149 



inferior. Both belong to the list of conglomerate glands. They are 
situated behind the upper eyelid, directly below the orbitar plate. 

The superior lachrymal gland {Gl. lachrijmalis superior, s. innomi- 
nala Galeni), is much larger than the other. It occupies the lachry- 
mal depression of the frontal bone. It is triangular, and flattened from 
above downward. The inferior ( Gl. congregate Monroi) ( 1 ) touches 
at its posterior extremity, the anterior part of the preceding, and 
extends to the external part of the upper edge of the cartilage of the 
upper eyelid: Its lobules are smaller and more remote from each other, 
than those of the upper. 

Six or seven very small canals arise from these two glands, and go 
from behind forward, from without inward, and from above downward, 
and open at the side of each other from without inward, on the inner 
face of the upper eyelid, near the external angle of the eye. 

B. LACHRYMAL PUNCTA AND LACHRYMAL PASSAGES. 

§ 1970. The upper and the lower eyelids present each, at the part 
where the inner angle commences, and where the orifices of the 
Meibomian glands terminate, an opening, the direction of which is 
rather more backward, and which may easily be distinguished from 
those of the palpebral glands and the lids, as its diameter is much 
larger, and as it is supported by a conical prominence. These two 
openings are termed the lachnjmal puncta (P. I. superius el inferius). 
The direction of the upper is downward, and that of the lower is up- 
ward. The latter is most generally larger than the other. 

These puncta are the orifices of the lachrymal jmssages (canahcuh 
lachrymales, s. comua limacum), which extend to the lachrymal sac. 

The lachrymal passages proceed directly on the edges of the eyelids, 
covered posteriorly by the internal cutaneous layer of these lids, arid 
anteriorly by the orbicularis muscle, with which they are so intimately 
connected, that they are detached from its fibres with great difficulty. 

The superior first ascends a little outward, in which direction also 
the inferior descends. In this part of their course they are very narrow. 
Then after slightly projecting, the superior goes inward and downward, 
and the inferior upward, and both converge very much. Arrived at 
the inner angle of the eye, they pass under the palpebral ligament, 
and open into the anterior and external part of the lachrymal sac, one 
directly above the other, but by two distinct orifices. They form within 
this cavity a small rounded prominence. 

A whitish and smooth mucous membrane forms their panetes. 

lachrijmale, Paris, 1821. 
(1) Loc. cit. t p. 77. 

Vol. HI. 20 



150 



DESCRIPTIVE ANATOMY 



C. LACHRYMAL SAC. 



§ 1971. The lachrymal sac (saccus lachrymalis) differs much in Us 
breadth, direction, and structure, from the lachrymal passages. 

It is infinitely broader than they, but it contracts a little from above 
downward. 

It is covered anteriorly by the inner part of the orbicularis palpe- 
brarum muscle, and is situated above in the lachrymal groove, along 
which it extends upward into the lachrymal passages by a small cul-de- 
sac, and downward into the nasal canal. It descends first from within 
outward and from behind forward, then, on arriving at the nasal canal 
its direction is from before backward. In its course its diameter gradu- 
ally diminishes. It opens into the anterior part of the lower meatus of 
the nasal fossae, by an opening which is oblique from above downward 
and from within outward, and which is provided with a small valve. 

It is formed of three superimposed membranes. 

The external is whitish, and is evidently fibrous, and also serves as 
a periosteum to the bones which receive the lachrymal sac ; but it is 
also very apparent on the anterior side of the upper part of the sac 
which lodges the lachrymal groove. 

The middle is thin and cellular : it corresponds to the cellular tunic 
of the mucous membranes. The internal is thick, rough, spungy, 
verrucous, and of a deep red. It always secretes an abundant mucus, 
which oozes through the rounded and oblong orifices of small glands 
arranged very compactly. 

This internal membrane is evidently the continuation of that of the 
nasal fossa?, while that which forms the lachrymal passages is con- 
tinuous with the conjunctiva, so that it establishes the limit between 
the eye and the nose.(l) 

(1) Horner has discovered a new muscle of the eye, the following' description of it 
ia extracted from his Treatise on General and Special Anatomy, vol. ii. p. 408. 

"The tensor tarsi is a small muscle on llie orbital face of the lachrymal sac. It arises 
from the posterior superior part of the os unguis, just in advance of the vertical 
suture between the os planum and the os unguis. Having - advanced three lines, it 
bifurcates; one bifurcation is inserted along the upper lachrymal duct, and termi- 
nates at its punctum, or near it ; and the lower bifurcation has the same relation to 
the lower lachrymal duct. The base of the caruncula lachrymalis is placed in the 
angle of the bifurcation. The superior and the inferior margins of the muscle touch 
the corresponding fibres of the orbicularis palpebrarum, where the latter is con- 
nected with the margin of the internal canthus of the eye, but may be readily dis- 
tinguished by their horizontal course. The nasal face of this muscle adheres very 
closely to that portion of the sac which it covers, and also to the lachrymal ducts. 
The lachrymal sac rises about a line above its superior margin, and extends in the 
orbit four lines below its inferior margin. The orbital face of the muscle is covered 
by a lamina of cellular membrane, and between this lamina and the ball of the eye 
are placed the valvula semilunaris, and a considerable quantity of adipose matter. 

As the bifurcated extremities of the muscle follow the course of the ducts, they 
are covered by the tunica conjunctiva. When this muscle is examined from be- 
hind, the eyelids being in situ, it becomes obvious that it is concave on its orbital 
surface, and consequently convex on the nasal ; that the muscle is an oblong body, 
half an inch in length, and about three lines wide, bifurcated at one end ; ana that it 



i HE M v r 151 

ARTICLE SECOND, 

GLOBE OF THE EYE. 

§ 1972. The globe of the eye (bulbus oculi),(l) often termed simply 
the eye, is formed like an almost regular globe. In the adult its 
diameter is about an inch : its length, however, exceeds its breadth and 
its height. It occupies the anterior part of the cavity of the orbit, but 
passes a little before it. It is surrounded in every part by an abundance 
of fat, and also by the muscles which move it, and which contribute 
with the optic nerve, and numerous blood-vessels, to retain it in place. 

It is formed by several superimposed membranes and the humors 
contained by them. In respect to the form and the texture of the 
membranes, and that of the nature of the humors, we may divide it 
into two parts, a posterior and- an anterior, the first of which is more 
extensive than the other. 

arises much deeper from the orbit than any acknowledged origin of the orbicularis. 
The superior fork, however, has a few of its fibres blended with the ciliaris. 

In regard to the use of this muscle. Its attachment to the posterior face of the sac 
is such, that it draws the orbital parictes of the sac away from the nasal, and dilates 
the sac, from the nasal face of the latter being- fixed to the bones. As this muscle 
has a cylindrical concavity on its orbital side, it is evident that when it contracts the 
fibres become straight, or nearly so, like the fibres of the diaphragm, and the cavity 
of the sac is enlarged after the same manner as the cavity of the thorax. A tendency 
to a vacuum being thus produced by it, the valves or folds of the internal membrane 
of the sac, permit the vacuum to be filled more readily through the puncta than 
from the nose; and the puncta being continually bathed in the tears of the lacus 
lachrymalis, both in the waking and in the sleeping state, the tears are constantly 
propelled through them by atmospheric pressure. The evacuation of the sac is no 
doubt accomplished by its own elasticity, and by the contraction of the orbicularis; 
probably in a chief degree by the latter^ because in persons who have epiphora, or a 
tendency to obstruction in the nasal duct, the accumulation of tears and matter 
principally take place at night, when the action of the orbicularis is suspended by 
sleep. For these reasons we should argue, that this little muscle is active all the 
time, both night and day. To Dr. Physick I am indebted for suggesting another 
use for this muscle ; that of keeping the lids in contact with the ball of the eye. Some 
persons possess unusual voluntary power of this muscle, of which I have seen two 
examples; one in a lady ; another in a gentleman, a student of medicine. In each 
instance the individual could shorten so much the internal angle of the eyelids, as 
to conceal it, along with the puncta, in the internal canthus of the orbit." 

Trasmondi, on the contrary, thinks that it acts on the lachrymal sac and passages;, 
that it compresses the caruncula lachrymalis so as to favor the excretion of the 
humor formed by its crypt3, and that it relaxes or also tenses the membrane, go as to 
increase or diminish the base of the lachrymal sac, and to force the tears into the 
nasal canal. (Notice sur la dicouterle dc deux nerfs da I'ceil humain ; in the Me- 
langes de chirurgie e'trangilre, Geneva, 1824, p. 415). Gery (Ibid. p. 453) does not 
agree with his fellow-countryman, and thinks with Horner, that this muscle serves 
to adapt the lids to the globe of the eye, and to direct the tears into the lachrymal 
sac. F. T. 

(1) C. A. Rndolnhi, Diss, de oeuli quibusdam partibus, Gripswald, 1801. — Id. 
Ucbcreinigc Theue des Auges in his Analomisch-physiologixriw. I 'nicrsiirhvngen, 
vol. i. p. 1-30. — Doellinger, lllustratio ichvognaphica oculi kumnni, Wmtzburg, 
1817. — Edwards, Sur la structure de Vceil: in the Bulletin dc la soc.philom., 1814, 
p. 21. — E. Hone and I 1 '. I'. .in >-, Observations micvoseopiques sur tti structure del'ceil ; 
in Phil, trans., 1822, p. ~h. and in Archiv. [finer, dc mid., vol. ii.p. 151. 



152 DESCRIPTIVE ANATOMY. 

The most external membrane is the cornea, the posterior part of 
which is the opaque cornea or the sclerotica, and the anterior, the 
transparent cornea. Next comes the middle membrane, the choroid, 
the anterior part of which is termed the iris, and below this is a 
third, the retina, which is a prolongation or expansion of the optic 
nerve. 

I. MEMBRANES OF THE EYE. 
A. EXTERNAL MEMBRANES OF THE EYE. 

§ 1973. The external membranes of the globe of the eye are much 
firmer and thicker than the others. Its form is determined principally 
by them. 

A. SCLEROTICA. 

§ 1974. The sclerotica, the opaque cornea, or the albugineous mem- 
brane of the eye (tunica sclerotica, s. albuginea, s. cornea opaca), covers 
the posterior part of the eye, and occupies about five sixths of its cir- 
cumference. It presents posteriorly, a little nearer its inner side than 
its centre, a round foramen, or at least it is much thinner there than in 
its other parts, and there presents numerous small cribriform openings, 
through which the fasciculi of the optic nerve communicate with the 
retina. It is terminated anteriorly by a broad rounded opening which 
recieves the transparent cornea. 

As it belongs to the class of fibrous membranes it is white, brilliant, 
fibrous, very elastic and solid. We may forcibly divide it into several 
layers : but these are united by intermediate filaments. 

The two faces are smooth. Numerous blood-vessels, the trunks of 
the twigs distributed to the inner part of the eye, intimately adhere to 
the external ; some of these vessels perforate it posteriorly, others more 
anteriorly at about its centre. They all proceed within its substance 
a greater or less distance, which is proportional to their own volume. 

Smaller openings in its posterior part give passage to the ciliary 
nerves, which penetrate from without inward between it and the 
choroid membrane. 

The sclerotica is not equally thick in every part. It generally 
diminishes much from behind forward. Posteriorly it is about a line 
thick, and about one half of a line at the edge of the transparent 
cornea. 

The membrane is thinner in the points which correspond to the 
attachment of the tendons of the recti muscles of the eye, than between 
these insertions. 

In the place where the optic nerve communicates with the globe of 
the eye, it unites very intimately with the envelop given to this nerve 
by the dura-mater. Although it is eight or ten times thicker, and also 



OP THE EYE. 153 

firmer than this envelop, we may however consider them as identical, 
since they do not differ essentially in regard to texture. 

§ 1975. Among the superimposed layers of the sclerotica, one may, 
be detached more or less easily from the others, and with greater 
facility in the early periods of life, than in the adult. This very thin 
layer is a prolongation, not of the pia-mater as has been supposed 
since Zinn's time,(l) but of the envelop sent by the arachnoid mem- 
brane to the optic nerve, and with which it is evidently continuous. It 
forms a small bursa projecting inward, around the cribriform plate, 
through which the optic nerve enters the eye, and is reflected from the 
circumference of this layer on the inner face of the sclerotica, with 
which it unites intimately, proceeding with it to its anterior edge. 

There is then between this layer and the sclerotica, exactly the 
same relation as between the dara-mater and the arachnoid membrane 
within the skull and the vertebral column, or, emplojdng a more gene- 
ral comparison, as between the hard substances, as the cartilages and 
the fibrous organs, covered with serous membranes and these mem- 
branes. 

The inner face of this internal layer of the sclerotica, is rather inti- 
mately united to the choroid membrane by a loose cellular tissue, and 
also by the nerves and vessels which pass through the external cap- 
sule of the eye. We may, however, especially some days after death, 
separate and remove the sclerotica, without injuring the choroid mem- 
brane. 



B. TRANSPARENT CORNEA. 

§ 1976. The transparent cornea (tunica cornea, s. cornea pellu- 
cida)(2) which surrounds the anterior part of the eye, differs from the 
sclerotica in its texture so much, that it is impossible to apply the same 
term to these two membranes. 

It represents a segment of a sphere which is a little smaller than 
that of which the sclerotica is the figure, so that it is more convex and 
projects slightly on the surface of the latter. 

It is always a little thicker than the sclerotica, and its thickness is 
generally uniform, except at its circumference, where it gradually be- 
comes much thinner, but only in a slight extent. Sometimes, how- 
ever, it is a little thicker in the centre than on the edge. Its posterior 
face always describes a concavity which corresponds exactly to the 
convexity of its anterior face. 

The conjunctiva extends towards the upper edge and the lower edge 
of its external face for about half a line, so that thjs external face is 
not perfectly round, but slightly elliptical. The upper face, on the 

(1) Zinn, loc. cit., p. 11 

(2) B. D. Manchart, Cornece oculi tunica ezamen anaiomico-physiologicum, Tn- 
bin^en, 1743. — Hoffbauer, Diss, de cornea ejusquc morbis, Berlin, 1820. — M. J. 
Chelius, Ueberdie durchsirlitigc Hornhaul de.s Avscrx, Carlsruhe, 1818. 



154 DESCRIPTIVE ANATOMY 

contrary, is entirely round. It terminates by a circular depression or 
groove which receives a prominent edge, situated on the limit between 
the ciliary ligament and the iris. 

It always becomes much thinner and is serrated at its point of union 
with the sclerotica. 

The two membranes are united in three different ways. 

Sometimes the anterior face gradually diminishes, so that the trans- 
parent cornea is partly covered by the sclerotica. 

Sometimes the two faces gradually become thinner, and the cornea 
is inserted in a channel grooved on the anterior edge of the sclerotica. 

Finally sometimes the internal face insensibly disappears, and the 
cornea rests a little on the anterior edge of the sclerotica. 

The first is the most common and the last the rarest arrangement. 

§ 1977. The transparent cornea is formed of several layers having 
between them a limpid fluid which are separated more easily than 
those of the sclerotica, and which are united by a loose cellular tissue. 

This fluid transudes after death. Its evaporation causes in part the 
opacity and collapse of the cornea, which then occur. 

The posterior face of the cornea is covered by a thin, pellucid, homo- 
geneous and slightly extensible membrane, which tears evenly when 
forcibly extended and is easily detached from it by a slight maceration 
or by boiling. ( 1 ) This membrane is attached to the edge of the cornea, 
and does not proceed at least sensibly on the iris. It has been termed 
the membrane of the aqueous humor (mem. humoris aquei) this term 
is inappropriate, as it does not seem to secrete the aqueous humor* (2) 

B. CHOROID MEMBRANE AND IRIS. 

§ 1978. Directly below the external tunic of the globe of the eye is 
another membrane of about the same extent and also composed of two 
halves differing in their organization. The posterior is termed the 
choroid membrane, and the anterior, which is much smaller, the iris. 

(1) B. Duddell, Treatise on the diseases of the horny coat in the eye, London, 1729. 
— J. Descemct, An sola lens crystallina cataractce sedes, Paris, 1758. — Id. in the 
Mem. des sav. etrangers, book i. — Demours, Lettre a M. Petit, Paris, 1767. — The 
details of the quarrel between Descemct and Demours, in regard to the discovery of 
this membrane, are given in the Journ. de med., 1769, 1770, 1771. 

* Professor Schlemm of Berlin, asserts that the cornea is well supplied with 
nerves : " They arise from the ciliary nerves which divide behind the ciliary lio-a- 
ment into a superficial and a deep-seated order of filaments. The latter are larger 
and more numerous, and are distributed to the iris ; the superficial however enter 
the sclerotica on a level with the ciliary ligament, from whence they extend forward 
to enter the groove of the edge of the cornea which is united with the corresponding 
border of the sclerotica, and traverse the posterior part of the cornea until they 
become lost by their extreme tensity upon that membrane." (Am. Journ. of the 
Med. Sciences, Nov., 18130, p. 211.) 

(2) S. Sawrey in 1807 claimed the discovery of this membrnne, which had been 
vaguely imagined by Duddell, nnd which in fart had been discovered by Demours 
or Uescemet. (An account of a newly discovered membrane in the human eye, Lon- 
don, 1807.) p. T. 



OF THE EYE. 155 



A. CHOROID MEAIBBANE. 



§ 1979. The choroid membrane (tunica vasculosa, s. choroidea)(l) 
corresponds to the sclerotica. It extends from the anterior edge of this 
membrane to the entrance of the optic nerve for which it presents a 
rounded opening and to which it is directly united, particularly along 
the course of the nerves and vessels, in its whole extent by rather a 
loose cellular tissue. The union between the two membranes is only 
interrupted here and there by the ciliary nerves and the long ciliary 
arteries, which proceed between them from behind forward. 

The inner face of the choroid membrane is not attached to the re- 
tina, although they are in direct contact. 

§ 1 980. Near the anterior extremity of the choroid membrane the 
mucous tissue becomes much thicker in the outer face of the mem- 
brane, and forms a whitish ring about one line broad, called the ciliary 
ligament, the commissure of the choroid membrane, Ch. (L. ciliare, or- 
bicidus ciliaris, cir cuius ciliaris, plexus ciliaris). This ring attaches 
the choroid membrane to the sclerotica more firmly than in the rest of 
its extent ; but it is united to the sclerotica much less intimately than 
to the choroid membrane, which is thinner in the part corresponding to 
it, so that the latter can be easily detached from the opaque cornea, 
while this is not the case with the ciliary ligament, which may conse- 
quently be considered as forming- part of it. 

The internal circumference of the ciliary ligament is bounded by 
a narrow but very evident white projection, which fits exactly into 
a groove on the circumference of the inner face of the transparent 
cornea. 

Before this ring is the iris, which is intimately united with it. 



B. CILIARY BODY. 



§ 1981. The inner face of the choroid membrane is singularly 
changed in this place, where it forms the ciliary body (corona ciliaris, 
s. orbiculus ciliaris, corpus ciliare, tunica ciliaris).(2) In fact on 
leaving the external edge of the ciliary ligament it forms, inward and 
for the breadth of about a line and a half, numerous small folds, whence 
come a great number of slightly prominent rays which go from with- 
out inward. Another smaller and more internal circle then succeeds, 
formed by more distinct folds, the inner edge of which is convex and 

(1) Ruysch, Ep. anat. xiii.— L. Heistcr, Diss, dc tunica choroided , in the Fasc. 
diss, med., Leyden, 1745. — B. S. Albinus, Dc tunica Ruysckiana et choroided oculi ; 
in the Ann. acad., 1. vii., cap. iv. 

(2) J. G. Zinn, De ligamentis ciliaribus programme!, Gottingeu, 1753.— Doellinger, 
Sur les procis ciliare's dans I' ceil de I'hommc ; in the JSov. acta nat. cur., vol. ix., 
p. 274. 



156 DESCRIPTIVE ANATOMY. 

which become more prominent from without inward, and terminate in 
a rounded edge. These folds, which are termed ciliary processes 
(processus ciliaris), are fewer in number although very numerous, as 
there are about seventy. They are however much more remote from 
each other than the external. Their anterior extremity is loose. They 
are attached to the large circumference of the crystaline capsule by 
the anterior part of their adherent edge. The posterior part of all this 
region of the choroid membrane adheres very intimately to the ex- 
ternal face of the ciliary ligament, for its folds are received into the 
depressions of this latter, the form of which corresponds exactly to 
theirs, so that in this part the inner face of the choroid membrane is 
firmly united to the subjacent parts, and when we attempt to detach 
it in the recent state the ciliary ligament is generally torn. 

§ 1982. The choroid membrane is soft and thin, but its tissue is 
firm and solid. On removing the coat of the pigment it appears 
whitish and slightly transparent. It is almost entirely formed by 
blood-vessels which are very distinct on its two faces, especially on 
the external. 

Some of these vessels are arteries and others veins,(l) but the latter 
are much more numerous. 

§ 1983. The arteries of the choroid membrane, termed the ciliary 
arteries (A. ciliares), are principally of two kinds. 

The long ciliary arteries (*3. ciliares longoz) are longer and more 
superficial than the others ; there are generally but two, an external 
and superior and an internal and inferior. These two arteries are 
situated more or less nearly opposite each other. After passing 
through the sclerotica at its posterior part they are situated on the 
anterior part of the choroid membrane, proceed directly from behind 
forward without sending off any very large branch, and are distri- 
buted in the iris. Hence they do not really belong to the choroid 
membrane. 

The short or posterior ciliary arteries, uveales, Ch. (A. ciliares breves, 
s. postcriores), are much smaller but more numerous than the long. 
There are usually twenty or more of them of different sizes. They 
perforate the sclerotica more posteriorly and internally than the pre- 
ceding, nearer the optic nerve, and soon enter the choroid membrane. 
They there divide into twigs which are given off at acute angles, 
frequently anastomose together, especially in the anterior part of the 
choroid membrane, and form forward, behind the external edge of the 
ciliary body, a circle composed of a very complex network. 

The twigs they produce in dividing are parallel, and proceed very 
closely from behind forward. At the posterior part of the choroid 
membrane they are situated on its outer face, but towards the centre 
of the globe of the eye they pass through it and go to its internal face, 

(1) J. E. Hebenstreit, De tasis sariguiferiis oculi, Leipsic, 1742.— J. G. Zinn Dc 
'casis subtilioribuz oculi et cochlea auris interna, Goltingen, 1753. 



OI THE EYE. 157 

where consequently they are more distinctly perceptible than in the 
external. 

§ 1984. The veins of the choroid membrane are easily distinguished 
from the arteries by their course and their larger size. 

Their branches are very compact, radiate from before backward and 
from without inward, form large arches, and divide into twelve or four- 
teen small twigs which pass through the sclerotica at about the centre 
of the globe of the eye, proceed a few lines from before backward in 
this membrane, and reunite in four or five larger trunks which pass 
out of the eye at its posterior part and enter the ophthalmic veins 
Four of these trunks are much larger than the rest, some of which 
proceeding also from before backward, receive the twigs coming from 
the iris. 

These veins have been termed from their numerous curves the vasa 
vorlicosa. They are more superficial than the arteries, and are also 
more external at the anterior part of the choroid membrane and form 
its external layer. 

Besides these veins there are others, the long or anterior ciliary 
veins (V. ciliares longai, s. anleriorcs), which accompany the long 
ciliary arteries, return from the iris, and receive no considerable rami- 
fications from the choroid membrane.(l) 

§ 19S5. The blood-vessels and the mucous tissue which supports 
them arc the only organic elements visible in the choroid membrane. 
Those fibres which are directed from before backward, and are ad- 
mitted by several anatomists to exist, have never been seen by us, and 
even the ciliary body seems only a very complex tissue of vessels. 
! § 1980. The internal face of the choroid membrane does not ap- 
pears perfectly smooth to the naked eye, but presents, particularly if 
the eye be injected, numerous small floating fiocculEe which give it a 
downy appearance ; this is much more evident if we use the micro- 
scope. These flocculre are very well developed in the ciliary body. 
They are mostly formed by a very compact tissue of vessels, particu- 
larly in the posterior region of the choroid membrane, the inner face of 
which is almost entirely covered by them, while they leave it much 
looser anteriorly. 

§ 1987. The internal face of the choroid membrane cannot be con- 
sidered as a special membrane in man, as we cannot divide it into two 
layers. Ruysch first asserted this opinion, while his son termed this 
coat the tunica Ruyschiana. It is also incorrect to admit as the villo- 
glandular tunic {2) or the supra choroid membrane (membrana supra- 
ckoroidea)(3), another membrane situated on the outside of the choroid, 
which would be the second middle tunic of the eye, or even the third. 

(1) See the plate of the vessels of the choroid membrane, in Scemmerring, Vebcr 
inste Gefcutsnetz vui im Augapfel, 1818. 

(2) B. A. Stier, De tunica quadam oculi novissime detecta, Halle, 1759. 

(3) Montain, in the Journal dc med., vol. lvii.— Bull, de la sue. m6d. d'Emul., 
1307, p 330. 

Vol III 21 



158 DESCRIPTIVE LNATOMT 

by admitting' the tunica 1 Ruyschiana, and which has been regarded aa 
belonging to the class of serous membranes.(l) 

Finally it is still move incorrect to represent the choroid coal at 
formed by five superimposed laycrs,(2) of which the second, third, and 
fourth form the proper choroid membrane, and tho other two the two 
membranes mentioned. 



§ 1988. The ins('-i) is a circular membrane perforated in its centr* 
with a rounded and nearly concentric opening, termed the pupil 
This opening is a little narrower on its inner side, which looks towards 
the nose, than in the rest of its course,(4) and its external edge is at- 
tached to the anterior edge of the choroid membrane, viz. to the ciliary 
ligament. Finally, it is entirely loose in the chamber of the eye, where 
it forms a transverse septum extended from above downward and from 
right to left, which divides this chamber into two compartments, an 
anterior and a. posterior, communicating by the opening of the pupil 

The iris forms the posterior wall of the anterior chamber of tho eye 
and the transparent cornea forms its anterior wall. It constitutes, on 
the contrary, the anterior wall of the posterior chamber, the posterior 
wall of which is formed by the anterior face of the crystaline lens, 
and the anterior edge of the ciliary body. 

Tho posterior wall of the iris is also termed the uvea. 

In man it is straight and not convex anteriorly, as has been as- 
serted. (5) It is nearer the anterior face of the crystaline membrane 
than the posterior face of the transparent cornea. (6) The space on 
its external face where it is greatest, between it and the crystaline 
membrane, is not even half a line, but in the centre it is only a quartei 
of a line. Its centre is about a line distant from the transparent cornea, 
but its outer edge is much nearer this membrane. 

Its extent from without inward varies extremely. It is not only often 
morbidly dilated to such an extent that the pupil almost entirely dis 
appears, and sometimes contracts so much as to be invisible or nearly 
so, but also in the normal state it dilates and contracts rapidly under 
the influence of certain external and internal causes. (7) By carefully 

(1) Doelling-er, loc. cit., p. 6. 

(2) Hovius, Dc circulari humorum motu, Leydcn, 1716, p. 29. 

(3) Maunoir, Memoirc sur V organisation dc I'iris, ct I' operation dc la pupillc arli- 
ficteUe, Paris, 1812. 

(4) Winslow, Observations sur la mlcanique des muscles obliques dc Pail, mm 
Piris, &c. ; in the Mim. de Paris, 1721, p. 463.— Littleton, Sur les causes d'ov 
depend la largeur de la pupillc ; in Bradley, Med. and phvs. Journal, vol. xxxvi 
p. 89. 

(5) Petit, Mem. sur les yeux geles, dans lequcl on determine la grandt 
chambres qui rev ferment Phumcur aqucsc ; in the Mem. do Paris. 1725 p 51 

(6) Ibid., 1728, p. 2U5 and 108. 

(7) J. G. Ziun, De motu urea: ; in the Com/m. Gott., vol. i. F Fontana, Dei moli 
delPiride, Lucca, 1765,— J. F. Blumenbach, /'■ cthiopum el motu 



OF THE EYE 



159 



examining all the circumstances which belong to these two pheno- 
mena we conclude that the active state of the iris is that of dilatation, 
the passive that of contraction. 

§ 1989. This membrane is much thicker in its larger and external 
than in its internal part, where it seems to be divided obliquely from 
without inward and from before backward, and terminates there in a. 
thin edge. The most internal part excepted, the iris is three or four 
times thicker than the choroid membrane. 

Its external and internal edges arc more deeply colored than the 
intermediate parts. The darkest part of the membrane is a small 
portion of the inner surface situated a little on the outer side of the 
inner edge. This dark place and the portion of the iris between it and 
the pupil is called the small or the internal circle (annulus minor, s. 
interntis). The rest of the membrane is termed the great or the ex- 
ternal circle {annulus' major, s. extcrnus). 

The whole of the anterior face of the iris is entirely colored. The 
posterior is colored only in the portion corresponding to the small 
circle : all the rest is whitish, but covered with a dark mucus (§ 1997). 
The anterior face is the seat of the peculiar color of the eyes. It is 
every where covered by very minute and differently colored flocculre, 
which with the streaks of pigment abovementioned on the posterior 
face are the grounds of the different color of the eyes. 

§ 1990. Wc observe both on the anterior and the posterior face of 
the iris circular fibres which are slightly undulatory, and longitudinal 
fibres which radiate from without inward. The first arc particularly 
evident near the outer and inner edge. The others are more distinct 
on the anterior face ; they are larger and more perceptible in the great 
than in the small circle. 

Some of these fibres are whitish and alternate with others less ma- 
nifestly gray. The first divide frequently at acute angles into a con- 
sidererable number of small branches, which anastomose on the outer 
circumference of the small circle, giving rise to arches which are convex 
forward, and thus form a complex crown from which smaller and closer 
longitudinal striae emanate ; these radiate in the internal circle to the 
edge of the pupil. 

§ 1991. The iris is soft and spungy. 

It is mostly composed of nerves and vessels united by mucous tissue, 
and very probably also of fibres, the seat of the contraction and dilata- 
tion mentioned above (§ 1988). 



iridis, Gottinpfon, 178!).— F. Hildebrandt, De motu iridis, Brunswick, 1780.— Doem- 
line, Ueber die Vrsache der Bewegung der Regenbogenhaut ; in licit, Archiv. fur 
Physiologic, vol. v. — Caldani, Int or no di rn.omm.enti dell'iride ; in the Mem. delta 
soc. ital., vol. xiv., pt. 2, p. 101-111.— C. A. F. Klugc, Diss de iridi motu Erford, 
1800.— S. S. Guttentag, De iridis motu, Breslau, 1815.— Littleton, On the causa 
which influence the izt oj thepupil; in the Land, run/ and phys. journal, vo 
1816, p 89 265 E. H. V 



160 DESCRIPTIVE ANATOMY 

§ 1992 The nerves of the iris (JV ct/tam)(l) arise from the first 

branch of the fifth pan, horn the sixth pan and the great sympathetic 

nerve, arc about twenty in number, and perforate the sclerotica a little 
behind the centre of the great diameter of the eye, pass some lines even 
in the substance of this membrane, are then situated between it and 
the outer face of the choroid membrane, adhere but slightly to these two 
coats, proceed from behind forward without giving off any branch, and 
arrive at the external edge of the ciliary ligament, directly behind which 
they generally divide nt, an acute angle into two branches. These 
branches go forward on the anterior face of the choroid membrane un- 
der the ciliary ligament and arrive at the anterior face of the iris, 
where they form the whitish and radiating filaments there observed , 
in the course of these are rounded filaments which arc perhaps gan- 
glions. 

The ciliary nerves are unusually large in proportion to the iris, and 
hence this membrane is one of the parts of the body, if not the very 
part, which possesses the most nerves. 

§ 1993. The vessels of the iris arise principally from the long or 
anterior ciliary vessels. 

Each of the two long ciliary arteries divides below the ciliary liga 
ment into two branches, which go to meet the two corresponding 
branches of the other arterial trunk, and which by anastomosing with 
them form on the external edge of the iris a crown slightly convex 
forward, from which numerous twigs arise ; the latter radiate towards 
the inner edge of the membrane and still bifurcate, communicating here 
and there by transverse ramuscules. They anastomose together on 
the outer edge of the internal ring so as to form at the opening of the 
pupil a more or less concentric circle ; from this, new radiating twigs 
arise and go to the small circumference, but several of them however 
come directly from the rays of the great external arterial circle. 

Besides the arterial twigs, the iris also contains many little veins 
which enter some into the long ciliary veins and others into the vasa 
vorticosa. As they cannot be filled except by injecting them through 
the arteries, or as when injected through the venous trunks, they arc 
filled less perfectly than the arteries, the veins seem fewer and form 
but small arches. (2) 

These vessels are most apparent on the anterior face of the iris, to 
which they seem but loosely attached. 

They certainly carry red blood, since the membrane [bleeds when 
wounded, and their reddish color is very evident in the eyes of albinos, 
where the pigment continues colorless from a primitive deviation of" 
formation. (3) 

§ 1994. Even in the most perfect injections, the iris still seems to be 
formed of more or less evident yellowish while fibres, which as we 

(1) Tiedemann, Diss, de ganglio ophthalmico ■ ! ■ ibus animalium Land- 
shut, 1815. 

(2) Zinn, loc. cit,, p. 04. 

(3) Monro. Veber den fiau <lcr Fische, Lcipsic, 1787, p. 74. 



»>F THE EVE 1G1 

have already stated, seem to be (he seat of the motions executed by 
this membrane, 

Several anatomists, as Drelincourt,(l) .Ruysch, (2) and Monro,(3) 
formally adopt this opinion, or are, like Zinn,(4) very much inclined 
to it. 

They assert that some of the fibres are radiated and others circular : 
the first extend from the external to the internal circle, where Ruysch 
tbinks that they arc even attached by small tendons : the circular form 
most of the internal circle of the iris.(5) In contracting, the longitu- 
dinal fibres dilate the pupil, while the circular contract it. 

Beside the circular fibres which are admitted by Monro and Ruysch, 
we have sometimes observed on the anterior face of the iris, towards 
its outer edge, some very evident circular fasciculi, corresponding to 
those discovered in the same place in the eye of the ox by Monro ;(6) 
but neither the anatomy, nor the observation of the vital phenomena of 
the iris, seem to us to justify the admission of radiating longitudinal 
fibres. 

§ 1996. The iris in man can be divided, but not naturally, into two 
layers, an anterior or the proper iris, and a posterior or the uvea, and 
these cannot be separated except in small portions. It is also uncer- 
tain whether its anterior face be lined by a prolongation of the mem- 
brane of Demours ; at least it is here also much thinner than on the 
posterior face of the transparent cornea, and its nature is different. 

§ 1 997. Opinions vary in regard to the manner in which the iris 
and choroid membrane are united. Some assert that the his is a pro- 
longation of the latter ; others think that it should be regarded as a 
distinct membrane. 

The arguments in favor of the second opinion are : 

1st. The greater thickness of the iris. 

2d. Its numerous nerves, while the choroid membrane has none. 

3d. The fewer vessels which carry blood to it, which differ in their 
origin and arrangement from those of the choroid membrane. 

4th. The difference between the two membranes in respect to their 
vital phenomena, since the iris is highly contractile, while the choroid 
membrane possesses no contractility. 

We may also add that the great edge of the iris is easily detached 
after a maceration, which does not continue long enough to destroy 
the continuity of the tissue either of this or of the choroid membrane. 

(1) Prcdud. anat. Opp. omn., p. 195. 

(2) Rcspons. ad cpist. anat. xiii , 'Me? anat. ii., p. 13-15. 

(3) Lac. cit., p. 110-115. 

(4) Loc. cit., p. 91 ,-.95. 

(5) Monro (loc. at., tab. 3). 

(6) Loc cit., tab. 2 



162 DESCRIPTIVE ANATOMY 



D. PIGMENT. 



§ 1997. The two faces of the choroid membrane mul the posterior 
face of the iris or the uvea, in the normal state, are covered with a 
brownish colored substance, termed the pigment (pigmentum ni- 
grum) (\) In some parts, particularly on the posterior face of the 
iris, this pigment can be detached in a greater or less extent as a fine 
and coherent membrane. In some places, particularly on the inner 
face of the ciliary body, especially between the processes, and the pos- 
terior face of the iris, and generally in the internal regions, it is more 
abundant, deeper in color, and more attached to the adjacent parts. 
There is less on the external than on the internal face of the choroid 
membrane, although that which exists there does not differ essentially 
from that found in other parts. There is none on the posterior part of 
the inner face of the choroid membrane around the opening which 
gives passage to the optic nerve, so that tho choroid coat is white in 
this place. • 

The pigment is composed of a peculiar mucous substance and of 
another coloring substance, the first of which connects all tho mole- 
cules together, so that they have the form of a membrane. In regard 
to mechanical structure, this coloring substance is composed of glo- 
bules. These globules are not perfectly black, but only present occa- 
sionally small points of a deeper tint. Their form is irregularly round. 
They are smaller in the ciliary processes, but are arranged in several 
superimposed layers more uniformly black. In regard to their che- 
mical composition, they contain a considerable quantity of iron and also 
of carbon, which forms almost half of them, so that of all parts of the 
body they contain the most of this elementary substance. (2) The 
iron is the cause of their heaviness but not the source of their color, 
since the quantity of this metal in the rete mucosum of the skin 
of the negro is small, and even less than in that of the Caucasian 
race. (3) 

The pigment is essentially so similar to the rete mucosum, that we 
may admit they are the same, whence it fellows that the pigment i> 
not a secreted fluid but a solid tissue, an organic element possessing a 
special form. 

(1) Mondini, De oculi pigmento ; in the Comm. Bonon., vol. vii., p. 29— Elsacssei , 
De pigmento oculi nigro, Tubingen, 1800.— L. Gmelin, Diss, sistens indagaiionem 
chimicam pigmenti nigri oculorum taurinorum et vittuinorum, adnexis ifuihusdam 
in id animadversionibus physidofficis, Gottingen, 1812 P Mondini, Sid nt 
mento dell' occhio ; in the Opuscoli scientifichi di Bologna, 1818, lasc. vii,. p I 

— Berzcliua, Djurkemi, ii., p. 201. 

(2) Berzelius, in the Med. chii (ran - I iii p 155.— Coli in Mondini jun., /oc. 
cit., p. 17. 

(3) Coli, loc. cit., p. 26. 



OB THE EYE, 163 



D. RETINA. 

§ 1998. The thud distinct membrane of the eye is the retina.(l) 
It, is the expansion of the optic nerve, the anterior extremity of which 
contracts much in passing through the sclerotica, but more gradually 
and more insensibly at its inner than at its outer part, so that the nerve 
describes an arch much larger outward than inward. 

Before the anterior extremity of the optic nerve the sclerotica pre- 
sents a surface with numerous foramina, through which the fasciculi 
of the nerves pass. Beyond this cribiform plate the extremity of the 
nerve forms a small mammillary prominence, from which the expan- 
sion of Ciie retina arises ; this terminates forward at the posterior ex- 
tremity oNlhc ciliary body by a straight edge more or less evidently 
enlarged, which is unconnected with the crystalline capsule. (2) 

§ 1999. The retina is white, thin, homogeneous, and destitute of 
fibres, equally thick in every part, excepting one small point of its 
extent posteriorly. It is composed, in a measure, of two layers, an 
external, which is medullary, and an internal, formed by cellular tissue 
and vessels. The latter separates the medullary layer from the vit- 
reous body. We cannot however insulate the two layers from each 
other so as to obtain one alone in the form of a connected and coherent 
whole, although the internal appears in this form when putrefaction 
has destroyed the medullary layer. Hence we cannot consider the 
retina except as formed by the union of two special and distinct mem- 
branes ; but we really find on its external face a very thin mem- 
brane(3) very analogous to the serous membranes, which seems to us 

(1) J. H. Mocller, Dc tunica nerved ct nervo optico, Halle, 1749. — B. S. Albinus, 
Dc tunica quam. vocant rclinam; in the Annot. acad., book iii., cap. xvi., Ann. 1756. 

(2) Several old anatomists, particularly Winslow, Cassebohm, Ferrein, Lieulaud, 
and Haller, whose arguments have been collected by Zinn (loc. cit, p. 114), and 
Monro among- the moderns (loc. cit., p. 96), have asserted that the retina passeg 
below the ciliary body, and that it extends to the great edge of the crystalinc cap- 
sule, to which it is attached. But careful dissections have led us to embrace the 
contrary opinion, which has been supported by Morgagni, Zinn, and some of their 
predecessors. Monro says that wc can prove that the retina extends to the crys- 
talinc humor : 1st, by resting the eye on the transparent cornea, and there making 
a transverse section which includes all the membranes with the vitreous body ; 2d, 
by raising the ciliary body and carefully removing the pigment with a pair of 
forceps. But in following these two processes wc have always recognized that the 
retina terminates evidently at the posterior extremity of the ciliary body, and we 
have even found that the layer still partially covered by the pigment, which extends 
from the hyaloid membrane to the crystalinc capsule, was more transparent than 
the retina. The eyes of the fetus are better than those of the adult to demonstrate 
that Monro's opinion io False, because in them the retina is more opaque, and thv 
external wall 01 the canal of Petit is thinner. 

(3) Jacob, Newly discovered membrane in the eye; in Thomson, Annals of pkilo- 
sophy, July, 1818, p. 74; Phil, trans., 1819, p. 300; Journ. compl. des sc. mid., vol. 
si., p. 187. — Jacobson, Mi: moire sur unc humeurpcu connuc dc I'ceil, et sur les ma- 
ladies auxquelles donnent quelquefois lieu les changemens survenus dans sa secre- 
tion; in the Act. soc. reg. med. aajh,, vol. vi. ; and Bull, dc la hoc. mid. d'JEmul., 
September, 1822.— G. Mirault, Sur une hydropisie particuliere uu globe dcl'aH , 
in the I 1. ii , p. 48, 



164 DESCKIl'TIVE ANATOM1 

to be the seat of ihe ossifications sometimes occurring between the 
choroid membrane and the retina. 

§ 2000. The retina is extended on the vitreous body, and forms 
there no fold, except in a small extent of its posterior part, at some dis 
tance from the entrance of the optic nerve, and on its outer side. 

There in fact tho membrane presents, a fold which is directed 
inward, a yellow spot, and a round place, where it is extremely 
thin.(l) 

The direction of this fold is transverse from within outward, li 
commences at some distance from, or directly at the side of the entrance 
of the optic nerve by a small point, and is terminated by a blunt extre- 
mity. It is generally from a line and a half to two lines long. It is 
commonly single, but sometimes also it is double. In some subjects it 
is deficient. (2) Home asserts even that it is never natural, and that 
its formation depends on the more intimate union in this place between 
the retina and the hyaloid membrane. But the error of the English 
anatomist is proved by the facts that the fold is observed even when 
the connections between the two membranes are unaltered, and that 
it is much more evident in youth than subsequently. 

The retina presents at the same place a yellowish spot of the same 
size, which is darker in the centre than on the edges. It is generally 
one line high, and from one and a half to two lines broad. But it 
has not the same extent and degree of color in every part, although 
these two peculiarities are not necessarily connected with the sense of 
vision. 

The retina is much thinner in this place than in the rest of its extent, 
particularly in the centre of the yellow spot, where some admit tbe 
existence of a foramen, while others, and according to our dissections 
more correctly, think that there is a place entirely destitute of medul 
lary substance, of an oval form and surrounded with smooth and dis- 
tinct edges. 

This thin place becomes very apparent only when the vitreous hu- 
mor is compressed to push the fold outward and to efface it. 

(1) Buzzi, in the Opusc. suite scienze c suite arti, Milan, vol. v., 1784, and vol. vii. 
— Scemmci ring", De foramina ccntrah limbo luteo cinclo rctincc hum ana ; in the 
(Jomm. soc. Gott., vol. xiii., 1795-1798.— P. Michaclis, Uubcr cinen gclbcn Fleck und 
tin Loch in der Nervcnhaul des menschiichen Auges ; in the Journal dcr Erjin- 
dungen, part xv., p. 1-17, 1796, and cab. xvii., p. 133.— J. C. Reil, Die Fallc, dcr 
gelbe Fleck and die durchsichtge Slclle in dcr Retzhaul des Augcs ; in the Archiv 
Fur die Physiolqgie, vol. ii., p. 468-797.— E. Home, An account of the orifice in the 
retina of the human eye ; in the Phil, trans., 1798, p. ii.— Expose' des remittals dc 
ptusieurs rechcrches sur la lache jaunc, le pli el le Iron central dc la ritine, d'aprcs 
deux memoires communiques par Marc ct Leveillc ; in the Mimoires dc la soc mid 
cPEm., vol. L, 1802, p. 364 397.— J. M. Wantzel, Veber die Home'schen Entdecicun- 
gen, das Loch, die Falte und den gelben Fleck im Mittclpunkl der Retzhaut 
hi trcjjeadc ; in Rosenmuller and Isenflamm, Bajtragen fur die Zerglicdcrurig- 
skiinst, Leipsic, 1800, vol. i., partii., p. 204 

(2) Kcil, toe. cit., p. 170. 



• UIE EYE. 165 



II HUMOUS OF X HE. LlL 



A. VITIIEOUS UUMOK. 



§2001. The posterior part of the eye is occupied by the vitreous 
humor or body (humor vitrcus, s. corpus vilreum), which corresponds 
in its situation to the choroid membrane and the retina.(l) 

This humor is perfectly transparent, thin, and formed almost entirely 
of water, which contains a small quantity of the hydrochlorates and 
the lactates, with still less of albumen and soda. (2) It is contained in 
a special, very thin, delicate, transparent membrane, which every 
where surrounds it, and which is termed the hyaloid membrane (tunica 
hyaloidca). This membrane sends internally numerous prolongations 
in the spaces of which the liquid is contained as in so many cellules. 
The union of the membrane and of the liquid which forms it, is pro- 
perly speaking, the vitreous body. 

This body presents on its anterior face a slight cavity which is con- 
nected with the crystalinc capsule, the posterior part of which is 
situated there, and adheres to it so intimately in the normal state that 
it cannot be detached from it, at least when the eye is perfectly fresh, 
without tearing the hyaloid membrane. 

2002. Between the great edge of the crystalinc capsule and the 
anterior part of the hyaloid membrane, a little behind the anterior edge 
of this latter, is a thin layer, termed the ciliary layer (lamina ciliaris, 
zonula Zinnii), which is extended like a bridge on the most anterior 
part of the vitreous body, in connection with which it circumscribes a 
triangular space, the base of which is formed by the posterior part 
of the circumference of the crystaline capsule, while the two branches 
are constituted, one by the layer, and the other, by the most anterior 
part of the vitreous body. 

This empty space surrounds the crystalinc and the vitreous body. 
It is termed the canal of Petit (canalis, s. cir cuius Petiti). It is easily 
demonstrated by inflating it with air. 



(1) P. Maitegiani (Nova: obs.de oculo humano, Naples, 1814, p. 19) admits be- 
tween the vitreous body and the retina an empty space, in the centre of which is the 
central artery of the retina, termed by him the area Martcgiani, in honor of hia 
father. J. Cloquet seems to admit the existence of this deviation, for he says (De la 
sauclctlopcc, Paris, 1819, p. 72,) that the hyaloid membrane is reflected on itself on 
a level with the entrance of the optic nerve into the eye, to form a canal which passes 
from behind forward directly through the vitreous body. He proposes to call this 
passage the hyaloid canal, and asserts that it always exists in man. F. T. 

(2) According to Berzelius (Animal fluids ; in (lie Med. cMr. trans., vol. iii., p. 
253), one hundred parts oi the vitreous humoi contains 9S,40 of water, 0,16 of albu- 
men, 1,42 of the hydrochlorates and lactates, 0,02 of 6oda and an animal matter 
completely soluble in water 

V o] III, 22 



166 DESCRIPTIVE ANAToiM\ 

The ciliary layer presents numerous fissures, the direction of which 
13 from before backward and from wilhin. outward, because it corres- 
ponds exactly to the inner face of the ciliary body, which is intimately 
united with it, and the folds of which arc situated in its depressions. 
Its external face seems blackish after the ciliary body is removed, be- 
cause the pigment remains attached to it there. When the canal of 
Petit is inflated, it is raised, its grooves become more superficial, and its 
external face seems formed of rounded or triangular eminences which 
project but slightly and are near each other. 

This layer is thicker than the hyaloid membrane ; still as it is united 
with this latter, and as the posterior edge of the layer is continuous 
with it, we have reason to say that the hyaloid membrane is divided 
at its anterior part into two layers, of which the external gives rise to 
the ciliary layer, while the internal is adapted to the posterior face of 
the crystaline capsule. 

Ribes(l) asserts that canals exist between the ciliary layer and the 
ciliary body, which canals conduct the aqueous humor in the chain 
bers of the eye, and take it up again from these two cavities. He 
supports his opinion by the dilatation of these pretended canals in an 
eye affected with hydrophthalmia, and the escape of the vitreous hu 
mor, when the eye is suspended by the optic nerve, after removing the 
transparent cornea. But these facts do not demonstrate it sufficiently 
The first phenomenon depends probably on the general accumulation 
of serum in the eye, a3 there is also a considerable collection of 
serum between the crystaline lens and the vitreous body. We have 
every reason to think that the second depended on the pressure of the 
vitreous body on a part which ought to yield more easily after cutting 
the transparent cornea. 



HI. CIIYSTALINE LENS. 

§ 2003. The crystaline lens (lens crislallina)(2) is a soft, rounded 
body, perfectly transparent in the normal state, the breadth and height 
of which are almost double its thickness, and the posterior face of 
which is much more convex than the anterior ; at least an inverse 
relation between its two faces rarely exists, and they are more fre- 
quently similar. The posterior face is generally a segment of a sphere 
about from six to nine lines in diameter, while the anterior is a segment 
of a sphere about five lines in diameter. 

(1) Mlm. de la soc. mvd. d'emul., vol. viii., p. 622-624. 

(2) A. P. Walter, De lente cristallinaoculi humani, Leipaic, 1712.- Petit, Mi 
sur le cristallin de I'aoil de Vhommc, des animaux a quatre pieds, des oi 
poissons ; in the Mem. de Paris, 1730, p. 1-33.— S. G. Sattig, Di /. nti 
structwa fibrosa, Halle, 1791— B. F. Baercns, Diss, si 

graphiam, 1819— Leiblein, B< en iibcr das System dct nryslallin 

gaughthieren und Vogeln, Wurzburg I !l 



OF THE EYE 167 

The thickness and the convexity of the crystaline lens are not al 
; iya in the same proportion, as there is no constant relation between 
these two qualities and the breadth and height of the lens 

The crystaline lenses of the two eyes in the same man sometimes 
differ very much in form. 

This body is situated before the vitreous body, the concave anterior 
face of which receives its posterior face, below the ciliary body, the in- 
ternal face of which is partly attached to its great edge It is situated 
behind the his, with which it is not connected. 

It however is not loose. A thin but solid membrane which is trans- 
parent and much thicker than that of the vitreous body exactly en- 
velops it in every part.(l) This membrane, termed the crystaline 
capsule (cnpsula cristallina), is the medium of connection between the 
crystaline lens and the adjacent parts, 

The crystaline lens is loose in its capsule. It is at most attached 
only by extremely minute vessels, which are detached from this mem- 
brane and enter its substance. 

Between it and the capsular membrane is a transparent and very 
this fluid, termed the humor of JWorgagni (liquor M.orgagnii).{2) 

§ 2004, The crystaline lens is formed of two substances, one ex- 
ternal and soft, the other internal and harder. These two substances 
blend together imperceptibly The first is termed the cortical layer, 
and the second the nucleus. The cortical substance can be easily 
separated from tho nucleus by crushing it between the fingers. 

A special process is necessary to demonstrate this texture ; but 
when the most complex means are employed, the crystaline lens is 
proved to be much more complicated than it seems at first view, and 
it may constantly be reduced into a certain number of parts (3) 

In fact by maceration and by the action of acids this body is divided 
in its whole extent from before backward into several triangular seg- 
ments, the summits of which are turned inward and the bases outward, 
and which unite in the centre of the lens. Besides each segment also 
divides into numerous small lamina), which are. situated one above an- 
other from without inward, and which cover each other like the coats 
of an onion, 

These layers are reflected from before backward on the outer edge 
of the crystaline lens, in the centre of which they accordingly termi- 
nate by two points, an anterior and a posterior. 

(1) Petit, De la capsule du cristallin ; in the Mim. de Paris, 1730, p. 022-643. 

(2) Graefe, Vcbcr die J'cstimmung dcr Morgagnischen Fouchtigkcit der Lin- 
scnkupscl und des Pcdtcnkranzcs ; in Kcil, Archiv, fur die Physiologie, vol. ix,, p, 

' 16, and in Abhandlungen dcr Erlanger Soc., vol. i. ( p. 389-396. 

(3) A. Lccnwenhork, De formatione humoris crystaltini in rariis animalibvs, de 
uostantia fibrosa qme in oado apparet, &.c. ; in the Art flat- detect, Delft, 1695, p. 

70. — Morgagni, in the E) Sattig-, Delentis crystallina 

rrosa, Halle 1793 Yovlb i"' ! 'i Morn.., Or, the 

wh ; ch enter into 
• it., p. 85. 



168 DESCRIPTIVE ANATOMY 

Their anterior half is often detached from the posterior, and the 
whole crystaline lens seems more or less evidently divided into an 
anterior and a posterior half by a fissure which extends from the cir- 
cumference to the centre. 

The layers which compose the crystaline lens are united by fibres 
which extend from one to another. They are likewise composed of 
fibres, the direction of which is parallel to their proper longitudinal 
diameter. These fibres consequently commence at the centre of the 
crystaline lens. Thus the tissue of the crystaline lens is lamellar and 
fibrous.(l) 

Between these layers is a diaphanous humor, more abundant on the 
outside than on the inside, which seems like that existing between the 
lens and its capsule. 

The segments of the crystaline lens in respect to their thickness 
and their lamellar texture, are more distinct on its outer than on its 
inner side. The fibrous texture is more evident in the inner part. 

§ 2005. The crystaline lens almost entirely dissolves in water, ex- 
cepting a small quantity of a transparent and insoluble membranous 
substance. Bcrzelius has found in it of one hundred parts : of water, 
58.0 ; of a peculiar substance, 35.9 ; of hydrochlorates, lactates, and 
animal matter, all soluble in alcohol, 2.4 ; of animal matter, soluble 
only in water, with some phosphates, 1.3; of insoluble membranous 
residue, 2.4.(2) 

It is particularly worthy of notice that, excepting the color, the pe- 
culiar substance which is coagulated by heat is perfectly similar in 
chemical composition to the coloring matter of the blood. It contains 
a little iron, while there is much carbon and iron in the pigment. The 
blood then seems to be decomposed, as the aqueous and vitreous hu- 
mors contain only the water which contributed to form it. Hence why 
these two humors do not coagulate. 

§ 2006. The crystaline capsule receives blood from the central artery 
of the retina and the vessels of the ciliary body. (3) 

The central artery of the retina is distributed in great part by its 
anterior branches on the posterior face of the capsule, for its last rami- 
fications on arriving at the anterior edge of the vitreous body are re- 
flected from without inward, and converge towards the centre of this 
face ; but there are also several small ones which pass on the ex- 
ternal edge of the capsule and go on its anterior face. 

The arteries which arise from the anterior edge of the ciliary body 
go exclusively on the anterior face of the crystaline capsule, and anas- 

(1) Berzelius supposes, but wrongly, that it also includes a membrane divided inlo 
several compartments by internal septa, like those of the vitreous body ( Djurki mi 
voL ii., p. 212). Finally, he observe?, and justly, that this body cannot be referred 
to the class of fibrous organs, as has liren done to a certain extent by Mayei ( I 
Histologic, p. 13), and by lleusioger unrestrictedly (Histotyfie, part i., p. 42), Binceit 
is entirely soluble in water. F T. 

(2) Loc. cit., p. 254. 

(3) J. G Walter, De vents ocut Berlii 



OF THE EYE. 169 

tomose there with the ramifications of the central artery of the retina. 
In the fetus they send off from behind forward numerous ramuscules, 
which are distributed on the posterior face of the pupillary membrane 

The vessels of the crystaline capsule and those of the pupillary 
membrane always correspond remarkably in regard to their arrange- 
ment and development^ 1) 

Finally the arteries of the capsule, especially those which arise from 
the central artery of the retina, send several very minute twigs to the 
lens which are distributed between its laminae, so that the latter are 
not nourished, at least entirely, by absorbing the liquid which sur- 
rounds them. 

Veins have not yet been strictly demonstrated in the crystaline cap- 
sule, although they a*e known to proceed on its posterior face. The 
latter empty into the veins of the choroid membrane, with which they 
open on the external face of the ciliary lamina.(2) 

Farther, in the normal state there is no red blood in the crystaline 
lens or in the vitreous body. 

We have not as yet discovered nerves in the crystaline lens nor in 
its capsule. 

B. AQUEOUS HUMOR. 

§ 2007. The aqueous humor of the eye (humor aqueus) is a per- 
fectly clear and transparent fluid which fills the two chambers. It is 
composed almost entirely of water,(3) and is formed very rapidly. 



ARTICLE THIRD. 



MUSCLES OF THE EYE. 

§ 2008. The eye is moved by six muscles. (4) Five of^hem arise 
from the floor of the orbit ; the sixth comes from the lower part of its 
anterior circumference. They surround the sclerotica, to which they 
are attached and blend with it.(5) 



(1) Hunter, in the Med. commentaries, London, 1762, p. 63, note. 

(2) Walter, loc. cit., p. 28, 29. 

(A) Bcrzelius (Djurkemi, vol. ii., p. 208) has found, in one hundred parts, 98.10 of 
water; some marks of albumen; 1.15 of hydrochlorates and lactates; and 0.75 of 
animal substance, soluble only in water. 

(4) C. Bell, Rccherchcs sur les mmivcmcns dc Pceil ct sur les usages des muscles 
et des nerfs renfermes dans P or bite ; in the Archiv. gin. de mid., vol. vi., p. 250 
and 445. 

(5) The aponeuroses which terminate them have been considered] but wrongly, as 
a special membrane between the conjunctiva and sclerotica. (E. Home and P. 
Smith, Philos. trans., 1795, no. i„ p. U, and no. xii., p. 262.) 



170 DESCRIPTIVE ANATOMY 

They are divided according to their direction into straight and 
oblique. The first are four in number. There are two oblique mus- 
cles 

I. STRAIGHT MUSCLES. 

§ 2009. The straight muscles of the eye (M recti bulbi oculi) are 
the superior, the internal, the external, and the inferior ; but beside 
these names, founded on the changes they cause in the situation of the 
globe of the eye when they contract, they have received others also, 
drawn from the expression they give to the countenance, and from 
the state of the mind which their action designates. 

Their common character, is that they all arise from the floor of the 
orbit by a short and thin tendon, and are attached to the anterior part 
of the circumference of the sclerotica by another thin but broad tendon. 

I, RECTUS SUPERIOR. 

§ 2010. The rectus superior muscle (JVf. rectus oculi superior, s. 
attollens, s. superbus), arises from the periosteum of the orbit, between 
the optic foramen and the upper sphenoidal fissure, between the upper 
part of the optic foramen and the sheath of the optic nerve, directly 
below the levator palpebree superioris muscle, It goes forward, rest- 
ing on the upper part of the globe of the eye, becomes broader and 
thicker from behind forward, and is attached by a broad but thin 
tendon, to the sclerotica alone, two lines above the transparent cornea 

It is the second in size among the straight muscles of the eye It 
is a little shorter but much thinner than the following muscle. 

It raises the eye. 

II. COMMON. TENDON OF THE OTHEfl THREE STRAIGHT MUSCLES OF THE EVE. 

§ 201 1 . The otfeer three straight muscles of the eye arise partly by a 
common tendon, or from a ligament which extends from the inner ex- 
tremity of the sphenoidal fissure, to two or three lines before this point 



III. RECTUS EXTERNUM. 



§ 2012. The rectus externus muscle (JVf. oculi rectus externus, s. ab- 
ducens, s. indignatorius) arises by two heads. The lower, the larger, 
comes from the external face of the common tendon, where it adheres 
very intimately to the tendon of the rectus inferior muscle. The up- 
per is much smaller, and is blended with the tendon of the rectus 
superior muscle, arises from the portion of the sphenoid bone comprised 
between the optic foramen and the commencement of the sphenoidal 
fissure. Hence, the muscle proceeds along the centre of the external 



OF THE EYE. 171 

wall of the orbit, situated on the periosteum, and is attached by a thin 
tendon to the outer part of the edge of the sclerotica, some lines from 
the edge of the transparent cornea It is broader at its centre than in 
the rest of its course, and is much flatter and thinner from without in- 
ward than from above downward. 

It is the largest, and particularly the thickest of the straight muscles 
of the eye : it is a little shorter, but infinitely thicker than the obliquus 
superior muscle. 

It ca/ries the eye outward, and acts when looking to the outside 

IV. RECTUS INFERIOR. 

§ 2013. The rectus inferior or the depressor oculi muscle (M. rectus 
oculi inferior, s. deprimens, s. humilis), unites with the lower head of 
the rectus extern us and rectus interims muscles, arises from the com- 
mon tendon, and never comes from the sheath of theoptic nerve. 
It goes from before backward, and from above downward under the 
optic nerve, and is attached to the sclerotica.. 

It is the third in size of the recti muscles of the eye, but it is thinner 
and shorter than the rectus internus muscle, 

It depresses the eye. 

V. RECTOS IMERNUS. 

§ 2014. The rectus internus muscle (JVf. rectus oculi internus, s. ad- 
ducens, s. amalorius, s. bibitorius) arises by iwo heads. The inferior 
or external comes from the upper and internal part of the common 
tendon. The superior or internal is the larger, and arises from the 
inner part of the sheath of the optic nerve. This latter blends with 
the origins of the rectus superior and the levator palpebrae superioris 
muscles. Thence the muscle goes inward and forward, along the 
inner wall of the orbit, from which it is separated by a la_yer of fat, Its 
short and thin tendon is attached to the inner part of the circumference 
of the sclerotica. 

It is the shortest of the four recti muscles, but it is thicker than the 
superior and inferior. 

It draws the eye inward. 

II. OBLIQUE MUSCLES. 

§ 2015. The oblique muscles of the eye (JVf. obliqui bulbi oculi) are 
distinguished into superior and inferior, They turn the globe of the 
eye on its longitudinal axis in opposite directions. 

1 OBLI40O8 SUPERIOR. 

§ 2016. The obliquus muscle, grand oblique, Ch. (J\I. 

oculi obliquus superior, s, lougus, s, trockkuris, patheticus), aiiscs from 



172 uESciurnvE anatomy. 

the posterior part of the inner face of the internal wall of the orbit, 
before the optic foramen, and also arises from the sheath of the optic 
nerve by a thin and short tendon. Thence it goes upward and forward 
along the upper edge of the internal wall of the orbit, and becomes 
near its anterior extremity, a long rounded tendon. 

This tendon immediately enters into a small cartilaginous layer 
about two lines long and broad, which is reflected on itself, and thus 
represents a semicanal, open upward, forward, and backward, and forms 
a pulley, the anterior edge of which becomes a pointed prominence, 
while the upper edges are attached by ligamentous fibres to the upper 
part of the internal wall of the orbit. 

The tendon is kept in this pully by a loose and movable cellular 
tissue. Its direction changes, so that on emerging it descends fioni 
before backward, and from within outward. It then becomes broader, 
and is attached to the inner and upper part of the sclerotica, on the 
mside of the tendon of the rectus superior muscle which partially 
covers it. 

This muscle is the longest and thinnest muscle of the eye. 

It draws the eye forward, inward, and upward. 

Sometimes, but rarely, it is more or less perfectly double. 

II. OBLIQUUS INFERIOR. 

2017. The obliquus inferior muscle, petit oblique, Ch. {M. oculi 
obliquus inferior), the shortest muscle of the eve, differs from the other 
muscles in its origin and direction. It arises by a short tendon from 
the inner extremity of the lower edge of the orbit, goes upward and 
outward, then becomes a short and broad tendon, which ascends below 
the anterior part of the rectus externus muscle, and between the 
muscle and the globe of the eye, and is attached to the sclerotica, some 
distance behind the tendons of the recti muscles, between that of the 
externus and that of the superior. 

It rotates the eye on its axis, first outward, then downward, and 
finally inward. It also draws the eye a little forward. 



A II TIC LE FOURTH. 

FUNCTIONS OF THE EYE. 

§ 2018. The eye represents an optical instrumental) composed of 
several transparent substances situated .successively from without m- 



Phil. trans., 1801, p. 81.— E. Mall, in the Journal of sciences and the arts, no. x. p. 
249-257.— A. Horn, The scat of vision determined, London, 1815.— M. T. Muhlibacli! 
fnquisitin de visits sensu, Vienna, 1816.— J. Purkinje, Beytrage -^ur Kenntniss del 
Schensin subjehtiver Binsicht, Trapse, 1810. Troxler, inHimly, OphihalBibf 



OF THE EYE. 173 

ward, which differ in density, although in all, this is greater than that 
of the atmosphere. The rays of light which enter it gradually con- 
verge on passing through it, so as to form but one fasciculus, which 
paints the image of the object at the bottom of the eye on the retina. 
The impression upon this membrane extends to the brain along the 
optic nerve, and there produces the sensation of sight. 

The transparency of the centres which form the eye, the sensibihty 
of the retina, and the conducting power in the optic nerve, are then 
the principal conditions necessary to sight. The opacity of one or 
several of the centres which concur to form the eye, the paralysis of 
the retina and of the optic nerve, the alterations in the texture of all these 
parts, the abnormal productions which are developed within or around 
them, consequently alter or destroy thejjense of vision. The globular 
form of the eye favors the refraction of 'rays of light. Hence, why the 
general form of the eye and of its different' parts very much influence 
the distance at which objects are seen clearly. When the eye is very 
convex, the rays of light are forcit|Ly, refracted, and we cannot discern 
objects which arc near (myopia). . When the eye is flattened the re- 
fraction is less, and only distant, objects are seen clearly (presbytia, 
presbyopia). Hence, why myopia belongs only to youth and infancy, 
and presbytia to old age. The eye possesses also the power of modify- 
ing its form, the relations of its constituent parts, its situation, and its 
direction, either to obtain a distinct view of objects situated at different 
distances, in a ray of a certain breadth, or to see without moving the 
head or body, those which occupy the different points of a portion of a 
surrounding sphere. This last effect is produced by the action of the 
six muscles of the eye. The other depends on the contraction of the 
muscles, partly on the modifications in the secretion and excretion of 
the humors of the eye, partly on the action of the ciliary body, since 
these three causes united change the curve of the transparent cornea 
and the crystaline lens, as also the situation of this latter in regard to the 
cornea and the base of the eye.(l) The dark color of the pigment 
tempers the violence of the impression which the light would other- 
wise cause on the retina, which is extremely sensible,(2) for this black 

vol. i. p. 21-99.— 

Physiologic, vol. 

ibid., vol. v. p. 97. 

E. E. Roedcobcck, Quadamad iheoriam visuspertinentia, Berlin,' 1822. 

(1) SiiBonoff hag ((included from calculations, that it is not necessary to suppose 
the crystaline lens displaced, and that the clearness of vision of objects situated from 
two hundred and fifty millimetres to'any distance, however great, depends only on 
their apparent diameters, and on the transparency of the air between. {Refutation 
dc lapritendue nicessite mathematique du deplacement du crista/! in pour conservcr 
constante la distance Jbcalc de Vail: in the Journ. dc physiol. c.rpcrim., vol. iv. p. 
260.) y T. 

(2) The sensibility of the retina is extreme only in regard to light. Magendie has 
determined that but a slight sensation is produced when this membrane is touched 
by a needle, and that even on scraping it, the pain is but slight, and not to be com- 
pared with that caused by pricking the surface of the eye. (Dc V influence de la, 
cinquicme poire sur la nutrition et les fond ions dcVce.il: in the ./burn. dephys.exp4r. t 
vol. iv. p. 170.) This physiologist has also determined that the section of the two 
nerves of the fifth pair causes the losa of sight. F. T. 

Vol. III. 23 



174 DESCRIPTIVE AWATOPir 

layer absorbs a part of the rays of light. This is the real function of 
the pigment, since vision is weak and imperfect when it has not its 
usual color. The iris also serves to moderate the intensity of the light 
which enters the eye, since this membrane dilates, and thus con- 
tracts the pupil, when the light is very vivid, or when we look at an 
object near, while it contracts and thus enlarges the pupil, when the 
light is weak, or when we look at rather a distant object. 



ARTICLE FITTH. 
DIFFERENCES IN THE EYE DEPENDING ON DEVELOPMENT, 

§ 2019. The eye differs considerably at different periods of life,(l) 
in respect to the existence, proportional volume, and form of the 
whole eye or of its parts. 

The eye appears very early. It is visible at the fourth week of 
pregnancy as a black spot. 

But at this period the globe of the eye is still exposed, for the eye- 
lids do not exist. They begin to appear during the tenth week, in 
the form of narrow bursae, which gradually enlarge. After about the 
twelfth week their edges touch, and they remain closed as in sleep 
until birth. 

The lachrymal puncta, and generally all the lachrymal apparatus, 
as also the Meibomian glands, are proportionally more developed 
during the early periods of life than subsequently. 

The eye is proportionally larger in the early periods of life than af- 
terward. The two external membranes, the sclerotica, especially 
its posterior part, and the transparent cornea, are proportionally 
thicker. This character belongs especially to the cornea, which is twice 
as thick as it is in the adult, from a considerable quantity of reddish se- 
rum existing between its layers, in the full grown fetus, so that its an- 
terior face is nearly plane, and the posterior touches the iris. It is also 
less transparent than subsequently. In old age it becomes planer, 
harder, denser, and more sobd : we also see developed, in old men, a 
nebulum, which extends from the edge to the centre (gerontonoxon, s. 
arcus senilis), which undoubtedly depends on the slowness with which 
the substance is renewed, whence the fluids have more tendency to 
coagulate ; this resembles those ossifications which supervene in old 
age in other parts of the body. 

The choroid membrane also is proportionally thicker, and the black 
pigment which covers it has a deeper tint. 

The pigment begins to appear very early at the fifth month of preg- 
nancy. But before birth it is less colored than in the adult : it adheres 
less to the choroid membrane and the iris : it does not exist on the outer 
face of the first of these two membranes, so that the intensity of its 

(1) J. G.Brendel, DefabricaoculiHnfcetibusabortiritobservala, Gottingen, 1752. 



OF THE EYE 175 

color and even its quantity seems to depend on the action of the light. 
In subjects at an advanced age, its color changes like the hair, and it is 
lighter, but the cornea and crystaline lens loose their transparency in 
the same proportion. The deeper color of the pigment in youth, 
depends partly on the fact, that the globules are nearer each other, 
partly also on their .being blacker at this period. They are also 
softer in young people, and hence they lose their form, and are de- 
tached from each other by drying. In the full grown fetus, the white 
cellular tissue existing between the vessels of the choroid membrane, 
contains no iron, while there is much in that colored black found in the 
same place in the adult. (1) 

The iris is one of the parts of the eye which varies the most at 
different periods ; the greatest change is the closing of the pupil by 
the pupillary membrane (membrana ptipillaris), or the membrane of 
Wachendorff, in honor of its discoverer.(2) 

The external edge of this membrane arises from the inner edge of 
the iris. It fills the whole pupil, so as to separate completely the pos- 
terior from the anterior chamber. It is a very tense, rather solid, but 
very delicate, thin, and transparent membrane, so that when its blood- 
vessels are injected, they cannot be perceived until the eye is hardened 
by immersion in alcohol. It is composed of two layers, the anterior of 
which is a continuation of the serous membrane which lines the an- 
terior face of the iris ; and the posterior is very vascular, and is con- 
tinuous with the posterior face of the iris. We have never known it 
to be covered posteriorly with a fibrous mucus, as Haller and Wachen- 
dorff assert. 

Some of its arteries arise : 

1st. From those which form the inner circle of the iris : they radi- 
ate from this circle towards the centre of the pupillary membrane, 
where anastomosing with the adjacent vessels, and not with those op- 
posite, they terminate and leave a small space in the centre of the 
membrane. They also anastomose with each other frequently in their 
course. 

2d. Other branches arise directly from the long ciliary arteries, pass 
on the iris, and go directly to the pupillary membrane, where they 
anastomose with the preceding. 

3d. Others still smaller arise from the vessels of the anterior face 
and from the greater edge of the crystaline lens, and are distributed 
principally on the posterior face of the pupillary membrane. 

(1) Coli, in Mondini, loc. cit., p. 17. 

(2) E. J. Wachendorff, in Comm. JSor., 1740. Helxl. 18. p. 137.— Haller, De nova 
tunica pupillam J actus claudenti ; in the Act. Upsal, 1742, and Op. min., vol. i. p. 
329. — J. G. Roederer, Defaetu perfecto, Strasburg - , 1750, § xxvi.— B. S. Albinus, De 
membrana pupillam infantis nuper nati prcecludente : in Anr,ot., acad. 1. i. cap. vii. 
— Vicq-tl'Azyr, Sur la membrane pupillaire dufcetus : in Hist, delasoc. roy.de mid., 
ann. 1777 and 1778, p. 257. — J. F. Blumenbach, De oculis leuccctkiopum et motu 
iridis, Gottingen, 1786. — H. A. Wrisberg, De membrana J'ostus pupillari: in Nov. 
comm. Gott.,\o\. ii. and in Syllog. comm. I. — Edwards, Surla structure de I' ceil : in the 
Bull, de la soc. philomatique, 1814, p. 21.— J. Cloquet, Mimoiresur la membrane 
pupillaire et sur la formation du petit cercle arUriel de I'iris, Paris, 1818.— Portal, 
Sur la membrane pupillaire : in Mimoires du Museum, vol. iv. p. 457. 



176 DESCRIPTIVE ANATOMY. 

Veins have not been demonstrated with certaint}'- on the posterior 
face of the pupillary membrane. 

The pupillary membrane passes through several periods of develop- 
ment. Its primitive form is not known, nor the manner in which it is 
produced, nor the period of its first appearance. 

According to Wrisberg it is not perceived distinctly before the third 
month of pregnancy. It is gelatinous and destitute of vessels until the 
fifth month, but at this period it becomes firmer and vessels are de- 
veloped in it. Perhaps, however, in the early periods of life it is 
greater in proportion to the rest of the iris, for the devolopment of the 
latter membrane begins at its external edge. 

It is most evident at the seventh month of pregnancy. It begins to 
disappear at the eighth month from the centre to the edge, that is, from 
the portion which has no vessels. In the full-grown fetus the only 
vestiges of this membrane are some small loose flocculac attached to 
the edge of the pupil. 

It generally disappears much sooner in animals born with the faculty 
of seeing than in those born blind ; it continues in these latter also as 
long as the eyelids remain closed. (1) The vessels are not destroyed 
with it. They contract from the centre toward the circumference ; 
their arches diminish, and they are finally adapted to the inner edge of 
the iris, where they form the small arterial circle, which does not exist 
so long as the pupillary membrane continues. (2) 

Although this membrane perfectly separates the two chambers, each 
cavity constantly incloses an aqueous humor, which does not exist in 
the posterior alone as Edwards(3) and Ribes(4) assert. We have 
demonstrated this perfectly,(5) and Cloquet after us. (6) 

A very curious periodical difference of the iris is a want of continuity 
of its circle, which is observed during the early periods of pregnancy, 
and which is very sensible at its inner part until about the seventh week. 

The retina is much thicker in the early periods of life than after- 
ward. This thickness does not depend on the greater development of 
its inner layer ; and so far from the medullary layer being propor- 
tionally thinner at this period, so far from possessing at that time less 
medullary matter, as has been asserted, (7) this substance on the con- 
trary is more abundant, and hence the increase of thickness presented 



(1) Meckel, Ucbcr die Dauer der pupillar Mcmbran ; in the Deutschcs Archir. 
fur die Physiologic, vol. i., p. 430 ; vol. ii. ; p. 136. 

(2) In demonstrating- this fact J. Cloquet has verified a conjecture of Blnmcn- 
bacn : Ejusquc (memSrarue pupillaris) vasorum clliptici circus sensim sent 
rcirahuntur, tuncque, ni graxilcr Jailor, annulum iridis intcriorcm efficiunt, cvjut 
ccrte ante cum tcrminum nullum in fectuum oculis vestigium reperire polui. (Inst 
ph>jsiol.,l7S7,p.2Q8.) 

(3) Loc. cit. 

(4) Loc. cit. 

(5) Loc. cit. 

(6) Loc. cit. 

(7) Brandis, Pathologic, Hamburgh, 1608, p. 241. 



OF THE EYE. 177 

by the membrane. In old men tho retina becomes extremely thin, but 
also more firm and resisting. 

We already perceive its fold in the sixth month of pregnancy, and 
even in the full-grown fetus it is greater than in the adult. The thin 
place is visible, but the yellow tint does not appear till some time after 
birth. It gradually becomes more intense, but turns paler as age ad- 
vances. It would seem that the fold diminished regularly and finally dis- 
appeared entirely. The less marked development in this region in old 
men is about in a direct ratio with the loss of transparency which gra- 
dually takes place in the cornea. The aqueous humor is turbid in 
the fetus. It becomes perfectly transparent during the first few weeks 
after birth. 

The crystaline lens also is much more convex in the fetus and in 
infancy than in the adult. At first it projects through the pupil, and 
thus pushes the iris before it, so that it is separated from the transpa- 
rent cornea only by this membrane, being situated in its special groove. 
In this respect and in the absence of the eyelids, the eye of the fetus 
resembles that of fishes. 

This arrangement, added to the great thickness of the transparent 
cornea, causes the chambers to be smaller and the aqueous humor less 
abundant than in the adult. All the humors, however, excepting the 
aqueous, are more abundant in youth than subsequently, whence it 
follows that the whole eye, and particularly the cornea, projects more, 
while as age advances, the eye slightly collapses and the transparent 
cornea particularly flattens. 

As age advances the crystaline lens assumes more consistence, and 
also becomes yellowish on leaving the centre, so that this tint is found 
generally in persons in advanced life. The same is true of the humor 
of Morgagni. At the same time this humor and that which fills the 
two chambers are slightly turbid, which is sometimes the case also 
with the vitreous humor. 



ARTICLE SIXTH. 



EYE IN THE ABNORMAL STATE. 



§ 2020. The situation of the ey"e exposing it to the action of all 
external causes of injury, and its extreme sensibility rendering it liable 
to be diseased from the influence of these causes, or to participate in 
the affections of other parts of the body, and finally its very complex 
structure, singularly multiply the number of the anomalies it may pre- 
sent ; these anomalies are more easily perceived even during life than in 



178 DESCRIPTIVE ANATOMY. 

most other organs, on account of its situation and the transparency of 
its parts.(l) 

I. DEVIATIONS OF FORMATION. 

§ 2021. Here, as in other organs of the botry, the primitive devia- 
tions of formation are the most remarkable in respect to the conse- 
quences deduced from them in regard to the general theory of organi- 
zation. 



A. PRIMITIVE DEVIATIONS OF FORMATION. 

§ 2022. I. The primitive deviations of formation in respect to quan- 
tity consist essentially in too slight an action of the formative power. 
They are : 

1st. Deviations in formation from defect in development. Here we 
may mention : 

a. The absence of the eye or of some of its parts. Here, as in the 
other organs, the conditions are not always exactly the same. In one 
case observed by Malacarne,(2) the optic beds and nerves, the common 
and the superior motor nerves, the globe of the eye, its muscles, the 
caruncula lachrymalis, and the optic foramina, were all deficient. The 
globe of the eye was replaced by a hard mass. The lachrymal appa- 
ratus and the eyelids were perfectly developed. 

In another case(3) the globe of the eye and the optic nerve as far 
as its bed and the optic foramen were deficient, but the accessory 
nerves and the lachrymal gland were present. 

b. Smallness of the ortran. 



(1) Beside the treatises on the diseases of the eyes, among which we may mention 
particularly those of Maitre Jean, Taylor, Janin, Rowley, Beer, Scarpa, Schmidt, 
and Himly, beside also the works already mentioned, because their authors have 
examined it both in the state of health and that of disease, we shall mention, on the 
pathological anatomy of this organ, the following : J. C. Sybel, Diss, de quibusdam 
materia: et forma: oculi aberrationibus a statu normali, Halle, 1798.— J. Wardrop, 
Essays on the morbid anatomy of the human eye, London, 1818. — Farre, A treatise 
on some practical points relating to the diseases of the eye, by the late Conningham 
Saunders, to uhich are added, &c, London, 1816— Dcmours, Traite des maladies 
desyeux, Paris, 1818.— Helling, Praktisches Handbuch der Augenkrankhciten, Ber- 
lin, 1721.— Baratta, Osserrazioni pratiche sulle principali malatti c dcgli occhi, 
Milan, 1821.— L. M. Mejra, Tratado tcorico y practico sobre las infermidades de los 
ojos, Orea, 1820.— B. Travers, Synopsis of the diseases of tlie eye, London, 1820.— 
J. Vetch, A practical treatise on the diseases of the eyc i London, 1820.— Consult also, 
on the pathological anatomy of the lachrymal organ, J. A. Schmidt, Ceber die 
Krankheitcn des Thranenorgans, Vienna, 1803.— C. H. Todc, Des maladies de la 
glande lacrymale ; in the Melanges de chirurgie LtransrCre, Geneva, 1S24. n 391 

(2) 'Isistcmi, Padua, 1803. If 

(3) Weidelc, in Himly, Ophlhalmolog. Bibliolhek., vol. iii., p. 2, p. 170. 



Off THE EYE. 179 

c The abnormal continuance of parts primarily existing, particu- 
larly of the pupillary membrane.(l) 

d. The adhesion of the two eyes. It is rather a general law in this 
case that the eye formed by the fusion of the two in one is situated 
directly on the median line, and is symmetrical in its structure. 

2d. Deviations in formation or in regard to quantity in an opposite 
sense when the body and head are normal, are very rare, and perhaps 
have never been observed. 

II. The deviations of formation in respect to quality are also rare. 
They affect most frequently the form of the iris and that of the pupil, 
which then is usually less round and most commonly perpendicular, 
rarely horizontal. This anomaly, often peculiar to certain families, 
and hereditary, is always curious as an analogy with animals. (2) 
The iris is rarely enlarged so much outward that the pupil does not 
correspond to the axis of the eye, being carried much more inward. (3) 

The transparent cornea is sometimes conical (staphrjloma conoides), 
and at the same time it is more or less thin. This state is its greatest 
degree of convexity, whence this includes also the greatest degree of 
myopia. 

Sometimes the cornea presents an opposite arrangement, being not 
sufficiently convex or entirely plane. 

B. ACCIDENTAL DEVIATIONS OF FORMATION. 

§ 2023. The accidental deviations of formation are more common 
than the preceding and very various, but they depend most generally 
on a previous alteration in the chemical composition, and the texture 
of the parts is then more or less changed. The principal deviations of 
this kind are : 

1st. Absence. Here we may mention the loss of the eyelashes and 
eyebrows, caused by the destruction of their bulbs, by inflammations 
and ulcerations of the eyelids. 

2d. Alterations in size. 

a. Smallness. In blindness, the whole eye or at least some of its 
parts, particularly the optic nerve and the retina, are often wasted. 

We have found several times in subjects who have been blind for a 
long time, that the retina was unusually thin and destitute of medul- 
lary substance in several parts of its- extent, this substance existing 
at intervals. 

When the power of vision is more or less diminished, the yellow spot 
also returns to the degree of color it presented before the eye was 
exposed to the light, for in this case its tint is more or less enfeebled. 

(1) See our Handbuch der pathologischen Anatomic, vol. i., p. 396. 
^2) See our Handbuch der pathologischen Anatomic, vol. ii., p. 158. 
(3) Demours, tab. lxiv., %. 1. 



180 DESCIlirTIVE ANAXOB1V. 

At the same time the fold is more or less cffaccd.(l) Sometimes to 
subjects affected with amaurosis the retina presents in this place black 
spots ;(2) but only the diseased eye undergoes this change ; the fold 
and the spot are on the contrary sometimes more sensible in that of 
the healthy side ;(3) the optic nerve is even sometimes larger than in 
the normal state. (4) 

The optic nerve is generally thinner and gray like horn. 

The transparent cornea sometimes becomes much flatter after dis- 
eases of long duration and excessive evacuations. 

The crystaline lens, left in the eye after separating it from its cap- 
sule partially or wholly, disappears very rapidly. At the end of a few 
years there is hardly a piece as large as a pin-head.(o) 

b. Enlargement. The eye sometimes enlarges so much from dropsy 
(hydrophthalmus), that it projects on the outside of the orbit. This 
dropsy is situated primitively in the vitreous body ; but it oxtends to 
every part, so that in some subjects we find considerable scrum be- 
tween the crystaline lens and the vitreous body. (6) Scarpa states 
that dropsy of the posterior part of the eye is usually attended with an 
increased secretion out of the vitreous body, as we have found several 
times on the inside of the choroid membrane and of the retina a great 
quantity of limpid serum, in which is a cord directed from before back- 
ward, formed by the morbid alteration of the vitreous body and re- 
tina^?) In this case probably the serum came from the serous mem- 
brane discovered by Jacob. 

A partial enlargement of the eye, often met with, forms staphfj 
101110,(8) a greater or less thickening of the transparent cornea, which 
causes the falling of this membrane, attended with its opacity, and 
depends on a previous inflammation situated in it. In this case the 
cornea generally adheres to the iris. The increase with the thinness 
of the sclerotica, which is much rarer and is also termed staphyloma, 
appears under the form of bluish elevations, the color of which depends 
on the varicose state of the vessels of the choroid membrane. It su- 
pervenes principally on the circumference of the transparent cornea 
after arthritic ophthalmia, but is observed more rarely at the posterior 
part of the sclerotica. (9) 

The lachrymal sac is more or less distended after inflammation of 
the lachrymal passages. 

3d. Solutions of continuity. 



(1) Michaelis, loc. cit., p. 8.— Reil, loc. cit., p. "472.— Leveille, in Wenzel, De.penit. 

struct, cereb., p. 167. 

(2) Wenzel, in Michaelis, loc. cit., p. 9. 

(3) Michaelis, loc. cit., p. 3. 

(4) Wenzel, Dc pen. struct, cercb., no. xi. 

(5) Scarpa, Malattic dcgliocchi, Pavia, 1801, p. 183. 

(6) Kibes, loc. cit. , . 

(7) Malattic degliocchi, p, 230. 

(8) J. L. Friedrich, Diss, dc slaphylumalc, Berlin, 1821. 

(9) Loc. cit., tab. ii., fig. 10.— Dcmours, loc. cit., tab. lxiv., fig. 3. 



OF THE EVE. 181 

a. Abnormal union This anomaly is ratfier common, and always 
results from inflammation 

When the conjunctiva has been violently inflamed and neglected, 
the eyelids join cither to the anterior face of the eye (sijmblepharon), or 
with each other (aucyloblepharon). Sometimes these two kinds ot 
adhesion take place simultaneously. The parts fused are sometimes 
nearer each other, and are often united by a greater or less number 
of accidental membranes which vary in length. Sometimes they 
adhere at birth. 

After inflammations of the iris, the pupil adheres (synizesis), or the 
anterior face of the iris unites to the posterior face of the transparent 
cornea, or finally the posterior to the anterior face of the crystaline 
capsule (synechia), by an effusion of albumen which coagulates, and 
which is sometimes distinct from the other parts in the form of a 
membrane. 

The obliteration of the ducts of the lachrymal gland is caused by 
external lesions on the outside of the eye. It depends on inflammation 
and ulceration, like the contractions of the excretory channels of the 
lachrymal humor. 

The shrinking (myosis) and the immobility of the pupil, observed 
after inflammations of the eye, very probably result from an effusion 
of albumen into its substance. 

b. Abnormal separation. The parts of the eye rarely present this 
anomaly except from external injuries. We however must arrange 
here the detachment of the crystaline lens observed after violent ce- 
phalgia and the fall of this lens into the anterior chamber across the 
pupil, which results from the percussion or commotion of the eye.(l) 

Ulcers produce especially in the transparent cornea, sometimes also 
in the iris, solutions of continuity, which, when situated in the first of 
these two membranes, cause the effusion of the aqueous humor and 
the falling of the iris. The iris is frequently detached in a greater or 
less extent from the sclerotica by a powerful shock : two pupils might 
then be said to exist. We must refer also to this head the abnormal 
enlargement of the openings, for instance, the pupil (mydriasis). 

Ruptures and other lesions of one or more excretory passages of the 
lachrymal gland form the lachrymal tumor (dacryops), the accumula- 
tion of tears between the conjunctiva and the globe of the eye, or a too 
great effusion of this fluid. 

Suppuration of the lachrymal sac frequently destroys & portion of 
it and its communication with the exterior, and thus produces fistula 
iachrymalis. 

4th. Deviations in situation. These anomalies extend to the whole 
eye, or affect some of its constituent parts only. The globe of the 
eye may be pushed out of the orbk by tumors in ns cavity (exoph- 
thatmia), and nuiy fall forward from the injujy 01 the paralysis of its 

(1) Kribault, Observailun ,ur aa cristallin qui a pass* pan le pupillt daiu la 
■hambre ant.cncurc de Pail ; in the Journ. dc mid , vol lix.. p. 72. 
Vol 111 24 



182 



DESCRIPTIVE ANATOMY 



muscles (oplilhalmoptosis), which changes more or lees the situation 
of the eyelids, and causes them to turn over outward. 

The direction of the eyelids alone is frequently changed, which may 
take place in two different modes, according as they are turned out- 
ward (cciropium) or inward (enlr opium). The latter effect is pro- 
duced particularly by the destruction of the internal layer of the skin 
of the lid and the cartilage, after inflammation of the eyelids, by a drop- 
sical state of these parts, sometimes by the paralysis of the levator 
palpebral muscle. This' paralysis however is never sufficient to cause 
it alone, it producing only the fall of the upper eyelid (blepharoplosis) . 
The first state is caused principally by wounds in the skin with loss 
of substance, sometimes also by the development of tumors and ex- 
crescences on its inner face. 

When the lid is turned inward, the eyelashes naturally "touch the 
globe of the eye. Hence it is called trichiasis, in which only some 
lashes participate, which occurs after inflammations of the eyelids, and 
arises from the inner part of the edge of the eyelids being destroyed by 
ulcerations. 

The prolapsus of the iris occurs in wounds of the transparent cornea, 
and when this latter membrane presents several openings through 
which the iris protrudes, a kind of staphyloma occurs which is termed 
the bunch of grapes. At first the protruded portion of the iris is ex- 
posed, soft, thin, and very vascular ; it gradually becomes solid, the 
circulation stops, and it is covered by a thin, grayish white membrane, 
which Beer regards as the regenerated conjunctiva ;(1) but it is more 
correct to consider it a new production formed by the exudation of the 
lymph from the iris. 

The protrusion of the membrane of the aqueous humor, admitted by 
most writers, is a prolapsus of the vitreous body, as Scarpa has per- 
fectly demonstrated.(2) 



II. ALTERATIONS IN COMPOSITION AND TEXTURE. 

§ 2024. Almost all the alterations of composition and texture in the 
eye, as in other parts of the body, depend on inflammation, to which 
this organ is very much exposed. Several of them however are de- 
veloped, and we cannot consider them as resulting exactly from pre- 
vious inflammation. 

Alterations in texture are very rarely congenital. We must, how- 
ever, regard as such the anomalies in the color of the eye, which may 
be referred : 1st, to a want of color in the pigment (leucocthiopia) ; 2d, 
to the different colors of the iris in the two eyes, or even in its different 



(1) Augenkrankkeiteri, vol. iL p. 63. 

(2) Loc. tit., p. 170. 



OF THE EYE. 183 

parts in the same eye ; 3d, to a want of transparency. Farar also(l) 
has observed, in three children of the same family, that the cornea at 
the moment of birth was clouded by a nebulosity, which afterwards 
gradually disappeared from the outside towards the centre. 

The new formations which must always, or at least in most cases, 
be considered as consequences of inflammation, are principally the fol- 
lowing : 

1st. In the eyelids. 

a. Grando, a rounded tumor, which varies in hardness and is de- 
veloped on or a little below the lower edge. It is a purulent cyst, a 
stye (hordeolum), not entirely destroyed by suppuration, and which is 
filled with coagulated albumen. 

6. Sarcoma of the eyelid, which is red and at first soft, afterwards 
harder, and which is developed on the inner face of the eyelids, parti- 
cularly in lymphatic subjects. 

Here we may mention the encanlhis, a tumor situated in the carun- 
cula lachrvmalis and the third eyelid. 

2d. In the conjunctiva. The film is a greater or less elevation which 
is developed between the anterior face of the sclerotica and the con- 
junctiva which covers it. The pterygium(2) commonly arises in the 
inner angle of the eye, where it extends outward to the anterior face 
of the transparent cornea, and beyond the centre of this latter. We 
rarely find a second or even a third in the external angle of the eye or 
in another region. It is more or less vascular, and its base always 
looks toward the circumference and its summit towards the centre of 
the eye, undoubtedly because the connection of the conjunctiva with 
the subjacent membrane is less intimate in the first place than in the 
second, where in fact it blends with the transparent cornea. 

The pannus differs from the pterygium as it is the substance of the 
conjunctiva, and sometimes also that of the transparent cornea, which 
thickens. The tumor termed pinguccida is generally developed in the 
external angle of the eye, or at least on the outside of the cornea. It 
is seldom larger than a bean, and it is formed by the conjunctiva and 
the subjacent cellular tissue. 

3d. In the transparent cornea(3) the principal results of inflamma- 
tion are macidcc and nebulae (obscuralio, albugo, s. leucoma), which 
sometimes arise only from simple exsudations in the tissue of the 
cornea, sometimes also are cicatrices of ulcers of this membrane, and 
vary in their extent and their degree of opacity. In the first case, the 
surface of the cornea does not differ at the spot where the point is, from 

(1) Med. communic, vol. ii., p. 463. 

(2) Beer (loc. cit., vol. ii., p. 038) does not consider the pterygium as resulting from 
an inflammation. We may however mention in support of this not only hi3 own 
opinion that the tumor usually appears when caustics arc applied (p. 640), but also 
Larrey'a observations, who remarked that it frequently was a consequent ol the 
Egyptian ophthalmia. 

(3) G. Mirault, Memoire surla hiratiteou inflammation :de la cornie transpa- 
rent; in the Arch. gin. de mid., vol. iii., p. 5. 



1H4 DESCRIPTIVE ANATOMY 

other parts; in the second it is deep The cicatrix is always hard, 
like the spot produced by an old exsudation. Farther we observe no 
other alteration of texture in the place where it is situated. (1) 

4th. In the iris the pupil is effaced (atresia pupillve) by an opaque 
false membrane, which causes at the same time the adhesion of the 
posterior face of the iris to the ciystaline (synechia) capsule. Then 
the production of pus or of a puriform fluid on the surface of the iris, 
whence a puriform congestion is formed in the chamber of the eye, 
which is termed hypopon. Scarpa thinks that it is real pus which 
forms bere, since we do not find in the iris an abscess the rupture of 
which could produce this purulent humor. (2) The serous nature of 
the two faces of the iris favors his opinion, but the authority of Ucer(3) 
at least authorizes us to doubt it as a general rule. 

5th. In the crystaline lens and its capsule, which are frequently the 
seat of cataract (cataracla, s. suffusio), which most generally renders 
opaque, parts normally transparent. 

Cataract varies in situation, consistence, and color. It usually arises 
from opacity of the crystaline lens (C. cristallina, C. lenticularis) , moie 
rarely of the crystaline capsule, especially of its posterior face (C. cap- 
sulaire } C. capsularis), still more rarely in the humor of Morgagni (C. 
laiteuse, C. JVEorgagniana, s. lac tea). These three kinds coexist in the 
capsulo-crystaline cataract (C. capsulo-lenlicularis). 

Opacity generally commences in the centre(4) and very deeply in 
the crystaline cataract, and on the contrary in the margin in the cap- 
sular cataract. Sometimes in the latter case only some parts are 
opaque, forming the clotted or mottled cataract (C. fenestrata). Most 
generally, but not always in old men, the crystaline lens is unusually 
hard, and in a measure ossified or petrified (C dura). It is rarely 
softer than in the normal state (C. mollis), or even fluid (C. jluidu) 
The capsule is more frequently hardened and thickened. Its anterior 
face is also covered in some cases (C. trabiculala, pyramidala) by a 
layer of substance, sometimes having the consistence of osseous tis- 
sue,(5) which arises from an exsudation formed by the inflamed iris, 
and which consequently can always be separated to a certain extent 
from the capsule. (G) The color of the cataract is most generally 
grayish white. 

In the crystaline and the capsular cataract, the crystaline lens and 
its capsule are not unfrequently detached from each other, or from the 
adjacent parts, by a shock of the body. But they arc sometimes con- 
nected more intimately, and so extensively that the crystaline capsule 
ond the iris adhere. 

(1) Wardrop, loc. cit., p. 03 

(2) Loc. cit., p. 149. 

(3) Loc. cit., vol. i., p. 43(i. 

(4) Rudolphi (Grundriss dcr Physiologic, vol. ii., p 184) mei lis a family in 

Berlin in which the central catarai ( (C ccntrali ) is hereditary; (his consists in a 
single dark point in the centre >f the crystaline lens which nary. 

(5) Beer, he. cit., p 303. 

(6) Beer, loc cit., p. 297: 



or THE EYE, 185 

In the pyramidal cataract the thick anterior wall of the capsule 
sometimes projects through the pupil and advances to the transparent 
cornea, to which it sometimes adheres. 

6th. In the vitreous body, the loss of transparency (glaucoma) and 
the complete dissolution of it (synchysis), which usually attend gutta 
serena.(l) 

§ 2025. The new formations developed in the eye are probably 
caused by an action similar to inflammation ; we cannot, however, 
always consider them as resulting positively from this cause. They 
are divided as in every other part, into those which are abnormal only 
from the place where they are developed, and those which are entirely 
new. 

1st. Among the tissues normally existing in other parts of the body 
we distinguish : 

a. The cellular tissue, which, assuming the form of false membranes, 
unites parts which are primitively separate, and which we have al- 
ready mentioned in this respect as produced by inflammation. 

b. The vascular tissue, which arises in the same manner in the dif- 
ferent new formations, especially in the preceding. 

c. The serous tissue, which is developed in the eyelids, especially 
the superior, in the form of cysts within the lachrymal gland in the 
orbit,(2) more rarely between the choroid coat and the retina. (3) We 
probably can arrange here the cysts formed on the surface of the iris 
when this membrane projects through an opening in the transparent 
cornea: 

d. The fibrous tissue, which occurs much more rarely. In one 
case the retina was changed into a white, fibrous, and very solid mem- 
brane, exactly similar to an aponeurosis, the external face of which 
adhered very intimately to an osseous layer between it and the choroid 
membrane. (4) 

e. The osseous tissue, which generally appears in the form of more 
or less irregular thin layers between the choroid coat and the retina, 
probably from the change of the serous membrane which covers the 
outer part of the choroid coat. It is seen more rarely in the transpa- 
rent cornea,(5) and it is probably developed primitively in the mem- 
brane of Descemet. 

We must probably mention here the considerable and petrous hard- 
ening of the opaque crystaline lens and the formation of stony concre- 
tions in the place of the vitreous body ; for the latter concretions, even 
when they become considerably thick, do not result from the change 
of the vitreous, body, but from between the choroid membrane and the 



(\) Heister, in the Act. nat. cur., vol. i., p. 71.— Demours, toe. cit., vol. i., p. 390. 

(2) Beer, loc. cit, vol. ii., p. 589, note. 

(3) Portal, Anat. mid., vol. iv., p. 418. 

(1) Magcndie, in Demours, loc. cit., 73, vol. i. 

(5) Walter, Amt.mvs., vol. i., p. 139.— Wardrop, tot, cit.. p 72.— Anderson, ibid., 

p n 



186 DFscmrTiVE anatomy. 

retina, and only push this body outward, since it is crowded and 
wasted in their centre.(l) 

/ Among the constituent parts of the cutaneous tissue the hairs 
are probably the only ones abnormally developed in the eye, unless 
we refer to it those cysts which form around hernias of the iris, and 
which we have referred to the serous system. The conjunctiva seems 
to be the only part of the eye where the hairs take root. They some- 
times appear also as abnormal eyelashes (dislichiasis) on the inner 
edge of the upper eyelid after neglected ophthalmias, and differ from 
the common lashes in their situation, thinness, smallness, and whitish 
color.(2) They are rarely developed in the conjunctiva of the eye, 
where they appear either in the conjunctiva itself, which is most 
usual,(3) or on the transparent cornea. (4) In the cases observed by 
Himly they were inserted in the centre of a fatty production, and in 
all other cases, at least those detailed by Wardrop, and Demours, a 
pterygium or film was the base of them, that is, they were preceded 
by a morbid change. Himly and Wardrop have observed this forma- 
tion in the external, and Demours in the internal angle of the eye. 
This latter case consequently resembles the considerable increase of 
one of the hairs of the caruncula lachrymalis, seen by Albinus.(5) It 
is curious that in the few cases of this anomaly as yet published, there 
is an evident connection between the period of puberty and the deve- 
lopment of accidental hairs. In the cases described by Wardrop, the 
hairs did not appear till the age of sixteen years with the beard, and 
in that described by Himly the tumor appeared at the age of two 
years, but did not become troublesome till the age of twenty, doubtless 
because hairs were not developed upon its surface. 
2d. The entirely new formations are : 

a. Figlike excrescences which appear in the iris, from syphilitic 
inflammation. 

b. Fungus hematodes, which is developed sometimes in the eye 
itself, and as it would seem on the posterior part of the choroid mem- 
brane, whence it goes forward, destroying before it all parts of the 
organ, and often extends to the outside of the eye in the fat of the 
orbit. Perhaps we ought also to arrange here the excrescences which 
are developed within the optic nerve. (6) 

c. The entozoaries. To these may probably be referred, at least 
sometimes, the loose hydatids which appear in the lachrymal gland, 
and which are explained better in this manner than by attributing 



(1) Scarpa, p. 269. 

(2) Beer, loc. cit., p. 119. 

(3) Himly, Ophihalm. Bib!., vol. iL, part i., p 199— Ware, On entropion, p. 7.— 
Wardrop, p. 31.— Demours, tab. Ixiv., fig. 1. 

(4) Gazelles, in the Journ. dc mid., vol. xxiv 

(5) Annot. acad., book iii., cap. viii. 

(6) Gallereux, in Demon re, vol, j.. p. 75. 



OF THE NOSE. 187 

them to a change of the cellular tissue.(l) The filaria Medinensis 
sometimes occurs below the conjunctiva.(2) 



CHAPTER III 



ORGAN OF SMELL. 

§ 2026. The senses of hearing and sight, the organs of which have 
been described, differ from the others in respect to their relations with 
other organs, as they are more independent. Those of smell and taste, 
on the contrary, are only portions of other organs, for they both belong 
tp the digestive system, and the first also to the respiratory system. 
It would then be proper to consider the organs of smell, voice, and 
respiration, of taste, and of digestion, as forming a single system. It 
is impossible to separate the history of the tongue from that of the in- 
testinal canal, since it is situated in a cavity, the commencement of the 
digestive apparatus, and in which the food is remarkably changed, 
since it is also situated behind the organs which cause these changes. 
But we shall consider the organ of smell separately, since it is more 
independent than that of taste, and after leaving the fishes it is entirely 
separated from the respiratory system, which in the three upper classes 
of animals communicates with the exterior, not only by the olfactory 
organ, but also by the oral cavity. 



ARTICLE FIRST. 



ORGAN OP SMELL IN THE PERFECT STATE. 

§ 2027. The organ of smell, or the nose, (3) is composed : 

1st. Of a bony cavity divided into several compartments, the upper 
and posterior part of which is more extensive, and is formed by bones, 
whence it is termed the bony nose (nasus osscus), and has already been 
described in osteology. 

2d. Of an anterior, smaller, triangular, elongated, and cartilaginous 
portion, the cartilaginous "portion (nasus carlilagincus) . 

3d. Of muscles which move this cartilaginous portion. 



(1) Schmidt, Krankheilen des Thranenorgans, p. 75. 

(2) Larrcy, Memoircs ct compagncs, vol. i., p. 223. 

(3) Santorini, Observationcs analomicce, Venice, 1724, cap. v., Dc naso, p. 84. — 
Ziervogel (Aurivillius), Dc naribun intcrnis, Upsal, 1760.— A. Scarpa, Anatomica: 
disquinitioncs dc audilu ct ulfaclu, Milan, 1795— T. C. Rosenthal, Dc organo ol- 
factus qxwrundcm animalium, Gripswald, 1807.— S. T, Scemmcnins, AbbUdungcn 
dcs mcnschlichcn Organs den Geruchs, Frankfort, 1809. 



188 DESCRIPTIVE ANATOMY. 

4th. Of a mucous membrane which covers the osseous and the car- 
tilaginous nose. 

5th. Of nerves which are distributed in this membrane. 

In considering the nose externally we distinguish an upper pal t ui 
the root, an anterior edge or the back, and a lower part or the tip. 



1. CARTILAGINOUS NOSE. 

§ 2028. The cartilaginous nose, the an tenor extremity of the bony 
nose, is composed of a central and perpendicular portion, the carlUagi 
nous septum of the nose (septum narium carlilagineum), of two ula, 
(pinna, s. alee nasi), finally of two oblong openings termed nostrUt 
(nares), by which the cavity of the nose opens externally, and which 
are supplied, especially on their inside, with stiff hairs (vibrissa'.) 

It is composed of several thin cartilages united with each olhci and 
with the bony portion of the nose, externally with the skin, internally 
with a mucous membrane. There are generally eleven. 

The largest, the cartilage of the septum, is perpendicular and square 
It completes the osseous septum anteriorly, where it is included be- 
tween the perpendicular plate of the ethmoid bone, the vomer, and the 
median suture of the two proper nasal bones. Its anterior edge dc 
scends from before backward, is loose, and is attached to a long pro 
longation of the skin, the cutaneous septum of the nose. 

The superior lateral cartilage is square and is attached to the lower 
edge of the proper nasal bone, to the ascending process of the superior 
maxillary bone, and to the upper edge of the preceding. It is generally 
blended with this latter so intimately that they form but one body.(l) 
Below this superior lateral cartilage, and at the side of the lower part 
of the median line, is the inferior lateral cartilage, or the cartilage of 
the ala (C. pinna), which is very low. This cartilage is narrow and 
formed of two pieces, an internal and an external, which unite forward 
at an acute angle, where they frequently present a foramen, and are 
sometimes entirely separated from each other. The external piece is 
longer and higher than the internal. Next come from before back- 
ward and from without inward several square cartilages ; these are 
much smaller, diminish in extent from before backward, circumscribe 
the nostril backward and outward, and are often blended with each 
other and with the preceding. From two to five other still smaller 
sesamoid cartilages (C. sesamoidea) are situated forward on each side, 
between that of the septum and the two lateral cartilages. 

(1) Santorini, luc. cit., p. 85. 



OF THE.NOSE 189 



II. MUSCLES OF THE NOSE. 

§ 2029. The cartilaginous nose is moved by a great many mus- 
cles,(l) two of which belong to it exclusively and two are common 
with the adjacent parts. 

A. LEVATOR ALjE NASI LABIIQ.UE SUPEBIOKIS. 

§ 2030. The levator alee nasi labiique superioris or the pyramidal 
muscle, grand susmaxillo-labial, Ch., arises from the nasal process of 
the upper maxillary bone, usually blends in this place with the frontalis 
muscle, descends in the side of the nose, and divides into two fasciculi, 
an anterior which is smaller, and is expanded in the lower lateral car- 
tilage ; the other is much larger, and blends with the orbicularis oris 
and the superior muscles of the upper lip. It raises the ala of the 
nose and the upper lip, and opens the nostril. 

B. COMPRESSOR NARIUM. 

§ 2031. The compressor narium muscle, stis-maxillo-nasal, Ch., is 
triangular, thick, and narrow at the base, and broad above. It ascends 
from the posterior part of the ala of the nose, where it is blended with 
the preceding, which partly covers it, and goes from behind forward 
toward the back of the nose, on which it unites with that of the op- 
posite side without any intermediate tendon. It often gives off at the 
upper part, a prolongation which blends with the frontalis muscle. 
This is the procerus muscle of Santorini, the lower part of his trans- 
versus nasi muscle. 

It contracts the nostrils when it acts from below upward, or from 
above downward, and never dilates them. 

C. DEPRESSOR AL2E NASI. 

§ 2032. The depressor aim nasi muscle, the proper muscle of the 
ala (JWT. pinnarum, s. narium lateralis, Santorini, s. dilator narium pro- 
prius, s. inferior), arises from the upper maxillary bone above the 
canine tooth and the external incisor. It is formed of oblique fibres, 
and extends almost the whole length of the outside of the cartilage of 
the ala of the nose. Its principal effect is to dilate the nostril when 
the nose is at rest. Being inserted in the upper maxillary bone, it 
can depress the nose. Finally, as its external face is attached to the 
integuments of the upper lip, it can also depress this latter: 

(1) Santorini, Obs. anat., cap. i., dc musculis faciei, p. 11. — Id., Tabuhc XVII., 
tab. i. — A. F. Walter, Tcncr. muse. hum. corp. anat. repel., Leipsic, 1731. — Isen- 
flamm ha.s described and figured them in hio Prafdische Anmcrkunge?i ubcr die 
Muskcln, Erlangen, 1778, p. 345. 
Vol. 111. 25 



190 DESCRIPTIVE ANATOMY. 

We sometimes find before it a proper, but much smaller muscle, to 
dilate the nostril ; it is called the myriiform muscle of Santorini, and 
sometimes surrounds the nose like a sphincter. 

D. DEPKESSOR NAKIUM. 

§ 2033. The depressor narium muscle forms on each side a small fasci- 
culus situated along the median line : it arises from the inner upper 
part of the orbicularis oris muscle, and is attached backward and in- 
ward to the inner branch of the cartilage of the ala of the nose. It 
draws the cartilaginous nose downward and backward, and also con- 
tracts the nostrils. 

III. MUCOUS MEMBRANE. 

§ 2034. The mucous, olfactory, pituitary, or Schneiderian mem- 
brane of the nose, has aot the same nature in all parts. The proper 
nasal portion is more than a line thick in some places ; it is thick, very 
red, and intimately fitted to the bones which it covers in every part ; it 
contains' numerous depressions and mucous follicles, and also at the 
lower and inner part of the nose, some small yellowish and distinct 
glands, which are imbedded -in its peculiar tissue. At the anterior and 
inferior part of the nose it is thinner, harder, drier, and also provided 
with mucous follicles. If we except this latter portion, the pituitary 
membrane is covered in every part with very short villosities. At the 
lower edge of the septum there is not unfrequenlly a narrow canal, 
the direction of which is from behind forward, terminating posteriorly 
in a cul-de-sac, and which opens at some distance behind the anterior 
edge, evidently above the organ of Jacobson.(l) 

The mucous membrane of the accessory cavities or of the sinuses, 
is externally thin, smooth, and yellowish white. It adheres but slightly 
to the surface of the bony cavities it covers, undoubtedly because nu- 
merous vessels and nerves do not enter it, through the substance of 
the bones. 

IV. NERVES. 

§ 2035. The nose receives its nerves from two sources, the olfactory 
and the second branch of the trifacial nerve. (2) 

The olfactory nerve is undoubtedly the proper nerve of the organ of 
smell,(3) since when absent or compressed, the sense of smell is lost. 

(1) Ruyscb, Thcsaur. anat. III. tab. v., fig-. 5.— Jacobson, Ann. du rnus vol 
xviii. p. 412. ■ 

(2) J. Hunter, A description of the nerves which supply the organ of smelling • in 
Obs. on different parts of the animal economy, p. 239, tab. ix-xviii.— A. Scarpa,' /oc 
cit., cap. iii-vi. *^ 

(3) Magendie has doubted the proposition generally admitted in a memoir en- 
titled "Le ncrf olfactif cst-il Vorganc de I'odorat ? In the Journ. de phi/s cratr 
vol iv. p 169." Mery already doubted that the olfactory nerve was the orfran of 
smell, and asserted that it was supplied by the fifth pair. (Brunet, Propria dc la 



OF THE NOSE, J 91 

From the lower face of the prominence which terminates it, two series 
of filaments arise, an external and an internal, which correspond to the 
two series of foramina in the cribriform plate of the ethmoid bone, 
although two or three of them frequently emerge through the same 
foramen. They vary much in number and size. There are from four 
to twelve. The anterior go downward and forward, the middle di- 
rectly downward, the posterior downward and backward. Shortly 
after leaving the olfactory nerve they enter the sheaths of the dura- 
mater, within which the posterior, particularly, pass a long distance 
before entering the foramina of the cribriform plate. They are covered 
first by the dura-mater, and flattened by the arachnoid membrane, 
which is less compact, and does not attend them as far. Entirely on 
the outside, each is surrounded by a tunnel-like prolongation of the 
dura-mater, which extends very far, and makes them apparently larger 
than they are on leaving the ganglion. They anastomose below the 
cribriform plate, descend between the bones and the pituitary mem- 
brane, soon ramify very much, and thus gradually approach the loose 
surface of the membrane. 

Part of the internal series belongs to the septum, the component 
nerves of which pass entirely through it : the middle are the longest and 
the posterior the shortest. 

They descend side by side, forming a single layer. 

The external series is distributed in the sides of the nose, particularly 
in the two superior turbinated bones, forms considerable anastomoses, 
but the filaments formed by these nerves are much less compact than 
those of the external : they do not enter into the ethmoid cellules, and 
do not go to the mucous membrane of the inferior turbinated bones, or 
at least send forward but few and very minute ramuscules. 

The olfactory nerve sends no filaments to the pituitary membrane of 
the sinuses. 

medccinc, 1697.) Having opened the skulls of three or four men, in whom the organ 
of smell during life was unaltered, he found the pair of nerves callous near the cere- 
brum. Loder, however, (Obscrvatio tumoris scirrhosi in basi cranii reperti, Jena, 
1779,) has seen the olfactory nerve destroyed in a man destitute of the power of per- 
ception, and Oppert also has observe?! the same thing in a female, in whom the sen6e 
of smelling was deficient (Diss, d^ritiis nervorum organicis, Berlin, 1815, p. 16). 
Cerutti (Beschreibung der palhologischen jPrdparate des anatomischen Theaters zu 
Leipzig, 1819, p. 208) mentions the cerebrum of a man who never possessed the 
faculty of smelling, in whom the olfactory nerve and its groove on the lower face of 
the inferior lobe were deficient. Tiosenmuller even has described this case (De de- 
J'cclu ncrvi olfac, Leipsic, 1817). But Rudolphi regrets, and with justice, that the 
turbinated bones of the septum were not examined, since in many cases, when it has 
been said to be deficient, it has been found, but very soft and diffluent. Farther, 
the facts related by Magendie, seem to give some weight to the old opinion ofMery ; 
at least they should draw the attention of physiologists to the sinuses of the nasal 
fossce, to which Malacarnc, -Weinhold, Blumenbach, and Treviranus, have attri- 
buted very different uses, which are sometimes very trivial, as those mentioned by 
Weinhold. It would be important to prove, whether, as Deschamps and Richerand 
assert from experiments made on subjects affected with diseases of these cavities, 
they are unconnected with the olfactory function; but ofthi3 we may doubt until we 
have more information, especially since the fine researches of Treviranus on the 
fifth pair of nerves. F. T. 



192 DESCRIPTIVE ANATOMY. 

Among the nerves of the fifth pair or the accessory nerves of the 
nose, the superior nasal nerves go backward, the middle and the in- 
ferior nasal nerves, and the nerve of the septum which arise from the 
pterygopalatine nerve, and the ethmoid nerve which comes from the 
nasal branch, go farthest forward, for they extend even before the ol- 
factory nerve, and are distributed in the mucous membrane of the nose. 
These nerves also surround the surface in which the olfactory nerve 
is distributed, and anastomose with its posterior and external filaments. 
Those from the second branch of the fifth pair communicate also with 
the ethmoid nerve. Hence, the accessory nerves form a complete 
circle around the expansion of the olfactory nerve, like that formed by 
the ciliary nerves around the retina. Although they proceed much 
farther, they however occupy much less space than the twigs of the 
olfactory nerve. 

§ 2036. The impressions of the odors are received by the olfactory 
nerve, and directly by the pituitary membrane. The portion of this 
latter in which the olfactory nerve is distributed, seems to be the prin- 
cipal seat of the faculty of perceiving them, although the membrane 
which lines the sinuses, partially contributes. 



ARTICLE SECOND. 

DIFFERENCES IN THE NOSE DEPENDENT ON DEVELOPMENT. 

§ 2037. We have already mentioned in osteology, the principal 
periodical differences in the bony nose. 

The whole organ long continues very imperfect. There is no trace 
of the external nose until the seventh or eighth week of pregnancy. 
At this time the nostrils appear, separated by a proportionally very 
broad septum, as two very small openings ; little later the nose begins 
to project over the mouth ; but during pregnancy it is blunt, and pro- 
portionally very small ; a large nose in an infant is very unpleasant, 
because it is a character foreign to the early periods of life. 

The cartilaginous structure of the external nose does not begin to 
appear till towards the end of the third i^nth. 

Until the end of the second, the nasal cavity communicates with that 
of the mouth. It is at first very narrow from above downward, and 
from right to left, on account of the greater breadth of the septum. 

The nasal canals are formed at the end of the second month, by the 
still membranous prominences of the turbinated bones. 



OF THE NOSE. 193 



ARTICLE THIRD- 

ORGAN OF SMELL IN THE ABNORMAL STATE. 
A. NOSE. 

§ 2038. The primitive deviations of formation in the nose(l) are : 

1st. Its entire deficiency, which is very rare, is generally attended 
with the fusion of the two eyes in one. 

2d. The union of the two halves of the nose in a tube situated 
below the single eye. 

3d. Greater or less openings in the septum. 

4th. Narrowness or closing of ihe nostrils. 

5th. The abnormal communication of the cavity of the nose with 
that of the mouth, by the deficiency of a greater or less portion of the 
palate. (2) 

6th. The more or less evident want of symmetry arising from an 
obliquity in the septum, which is sometimes so great that this latter 
even touches the wall towards which it inclines. 

Most of these primitive deviations of formation are developed also 
consecutively during life, after the bony and musculo-membranous 
parts of the nose and palate are destroyed by syphibs. 

The most frequent abnormal formations are the polypi of the pitui- 
tary membrane. Hydatids are infinitely more rare. They sometimes 
become so large that they considerably contract the nasal cavity. (3) 

B. SINUSES OF THE NASAL F0SS.E. 

§ 2039. The accessory cavities or the sinuses of the nasal fossm, pre- 
sent numerous and frequent anomalies. (4) 

Their deviations of formation consist in their absence and narrow- 
ness, which are usually congenital. Sometimes these sinuses do not 
communicate with the nasal fossre : but this anomaly almost always 
occurs, consecutively, after inflammation. (5) 

Once, however, we found in the cadaver of an old woman the two 
maxillary sinuses completely closed, without any pathological change 

(1) Deschamps, Traitc des maladies des fosses nasales ct dc kurs sinus, Paris, 
1804, £ft. 

(2) Portal, Anal, mid., vol. iv. p. 499. 

(3) Idem, loc. cit. 

(4) L. H. Rungc, Dc morbis prcccipuis sinuum ossisfrontis ct maxilla; supcrioris, 
Rintcln, 1750.— Bordenave, Sur les maladies du sinus maxillairc ; in the JMcm, dc 
Vac. de chir., vol. iv. p. 329.— C. A. Weinhold, Ucbcr die krankhaftcn Mctamorphoscn 
der llighmorshbhlc, Lcipsic, 1810.— P. D. Wagner, Diss, dc polypis narium ct antri 
maxillaris, Berlin, 1821. 

(5) A. F. Rohowsky, /' > c ibliter at ianc, Berlin, 1815— OUo, Vatho- 

itomie, p 203, arm. 15. 

\ 



194 DESCRIPTIVE ANATOMY 

in the texture of the pituitary membrane, and their surface also was 
moist as usual. 

A greater or less quantity of liquid, however, often collects within 
them, from the effect of certain causes ; this more or less forcibly dis- 
tends them, their parte tcs become thinner, and are finally destroyed 
when the compression continues a long time, although this state does 
not deserve the name of dropsy of the maxillary sinus, because the 
effused liquid is not of the same nature as that exhaled by serous mem- 
branes^ 1) 

Entirely new formations, as fibro-cartilages and polypi, either alone 
or united, are not unfrequently developed in the accessory cavities of 
the nose. These formations are particularly common in the maxillary 
sinus, which is the most subject to morbid alterations, doubtless on ac- 
count of the nearness of the teeth, and because the situation of its 
opening renders the escape of its secreted fluids more difficult. We 
may, however, blend them with the analogous tumors which are deve- 
loped out of the antrum Highmorianum, in the zygomatic fossa. (2) 



SECTION II. 

OP THE VISCERA OR FORMATIVE ORGANS. 

§ 2040. The viscera,(3) which may also be called the formative or- 
gans, because their essential function is to form new substances, pre- 
sent several general characters, the principal of which are as fol- 
low: 

1st. They are situated principally in the trunk, and occupy only a 
small part of the lower region of the face, and are generally placed in 
cavities formed by bones, muscles, and serous membranes, which vary 
much in capacity. A n aqueous vapor is effused between them and the 
parietes of these cavities. 

2d. They are entirely, or at least in great part, and in their most 
important portions, enveloped by serous membranes. Each system is 
separated in this manner from the others, and each occupies a distinct 
section of the trunk. 

3d. They receive most of their nerves from the ganglionnary sys- 
tem, and their nerves are always proportionally larger than those that 
go to the organs of sense, excepting always certain parts, as the tongue 
and the external organs of generation, which being abundantly sup- 
plied with nerves, possess a very acute and special sensibility, and are 

(1) Runge, loc. cit. — Fauchard, Chir. dentiste, vol. i. — Sauve, Cos d'hydropisie 
du sinus maxUlairc ; in the Bull, de lafac. de Tried., 1818, p. 9. 

(2) Lesage, Sur unc turneur enkystec de la fosse zygomatiaue prise pour un polype 
du sinus maxillaire ; in the Bull, de lafac. de med., 1816, vol. v. p. 268. 

(3) R. C. de Garengeot, Splanehnologie, ou V anatomic des visccres, Paris, 1712.— 
Gavard, Traitc de splanehnologie, Paris, 1809.— Boyer, Traits de splanehnologie, 
Paris, 1815. 



OF THE VISCERA. 195 

in fact, real organs of sense. Most of the viscera receive their nerves 
from the ganglionnary system, and next from the pneumogastric nerve ; 
but the hypoglossal, the glosso-pharyngeal, and the trifacial nerves, 
are also distributed in their upper portion, and the inferior spinal nerves 
in their lower portion. 

The nerves usually pass some distance before arriving at the organs, 
and generally each of the latter receives nerves from one pair only. 
One pair of nerves is distributed in part to se«ral organs. 

4th. The course of the nerves in most cPtheir extent is constant. 
As this condition does not exist in regard to those organs which re- 
ceive their nerves from the ganglionnary system, we must conclude 
that it does not depend on the nature of this nerve. It is false that 
the spiritual principle is not connected with them, and the changes 
that take place in them are not perceived ; this perception is very mani- 
fest in disease, and the sensalions that result from them are not more 
vague or obscure than those ascribed to all the organs except that of 
sight. 

5th. All the viscera are not united, at least in the perfect state, by 
mucous membranes. The respiratory and digestive systems commu- 
nicate together in the neck, the urinary and genital systems in the 
lower part of the trunk ; but the two latter are separated from the di- 
gestive system, or at least are connected with it only by the skin. 

6th. These organs are much less symmetrical as to form and situa- 
tion, than those of the senses. 

7th. Their most important part is more or less evidently glandular. 
All are formed by several glands, the combined action of which is to 
correct the fluids secreted by them. The necessity of the combined 
action of several glands is very evident in the most complex system, 
that of digestion. Next come in this respect the genital organs, espe- 
cially those of the male. The concurrence of several glands to form a 
new substance, seems least necessary in the urinary and respiratory 
systems. 

A second part is composed of a canal formed of several different 
superimposed membranes, united by cellular tissue, and with which 
the gland or glands in general communicate, and which is sometimes 
open at its two extremities like the alimentary canal, or at one only, 
like all the others. The nature of the parietes of this canal varies ex- 
tremely ; they are, however, always formed of at least two superim- 
posed layers, the external of which is condensed cellular tissue, and the 
internal a mucous membrane. The mucous membrane is covered 
sometimes in every part, as in the alimentary canal, sometimes here 
and there by a muscular tunic. 

8th. These organs, if we except the genital organs, are, next to the 
centres of the nervous and circulatory systems, the most necessary for 
the support of life, although some of their parts may be primitively de- 
ficient, or be destroyed in some manner without occasioning severe 
accidents, and although very considerable alterations do not occasion 
immediate death. 



196 DESCKIPTIVE ANATOMY 

CHAPTER I. 

OF THE DIGESTIVE ORGANS. 

§2041.. The digestif organs comprise an uninterrupted canal 
open at its two extremitjs, and several appendages„which communi- 
cate directly or indirectly with different parts of this canal, within 
which they empty a fluid prepared by them. 

This passage is termed the alimentary canal or tube (canalis, s. 
ductus cibarius). Its upper extremity is the mouth {os), and the lower 
the anus ; both are situated opposite each other, and nearly on the 
same line. The canal is imperfectly divided by valvular prominences 
into several separate portions, which are named according to their 
form or functions. It is very convenient to admit three parts, which 
differ in functions, structure, and situation, but which are all repeti- 
tions of the same type ; these are the upper, the middle, and the lower 
portion. The first occupies the head, the neck, and the chest ; the 
other two, which form most of the digestive system, fill almost entirely 
the cavity of the abdomen. The upper portion is composed of the oral 
cavity (cavum oris), the pharynx, which is smaller than the mouth, 
and the esophagus {gula, cesophagus), which is still narrower, and with 
which the pharynx is continuous. Directly after passing through the 
diaphragm the alimentary canal enlarges to form a second pouch, 
called the stomach (ventriculus, stomachus), which is the commence- 
ment of the middle portion. Next comes a second narrower portion, 
the small i7itesline {intestinum tenue), which is divided, from slight anil 
inessential differences, into the duodenum, the jejunum, and the ileou. 
The latter is continuous with the terminating portion of the intestinal 
canal, the large intestine or the colon {intestinum colon, s. crassum), 
which is divided according to the situation and direction of its different 
parts into an ascending, a transverse, and a descending colon. The 
latter is continuous also with the rectum, which opens at the anus. 
The small and the large intestines are termed the intestinal canal 
{ductus, s. canalis intestinalis). 

The appendages of the intestinal canal are glandular organs re- 
sembling conglomerate glands ; they are, the salivary glands and the 
liver. 

The salivary glands (G. salivares) are situated around the cavtiy of 
the mouth, into which their secretion goes, and in the abdominal ca- 
vity near the upper extremity of the small intestine. They are con- 
sequently divided into the oral and the abdominal salivary glands (6'. 
salivares orales et abdominalcs) . 

The liver (jeeur, hepar) also occupies the cavity of the abdomen. 
The fluid it secretes is termed bile, and is poured into the duodenum 
near the last salivary gland. 



OF THE DIGESTIVE SYSTEM. 197 

We also find in the abdomen a glandular organ, which has no ex- 
cretory canal, called the spleen (splcn, lien). 

All the portions of the digestive system in the abdomen, except the 
lower part of the rectum, are surrounded by a common serous mem- 
brane, the peritoneum. 

§ 2042. The alimentary canal(l) presents several general charac- 
ters which are simply modified in its component parts. 

The tube it represents is formed of several layers which belong to 
different systems, so that each concurs specially to the general func- 
tion. 

The most internal and the most essential of these layers is the mu- 
cous or villous membrane (tunica mucosa, s. intima, s. cribrosa, s. 
villosa). It is soft and more or less vascular, incloses numerous small 
culs-de-sac or small muciparous glands, and its surface is moistened 
by the mucus which it constantly secretes, and a thinner fluid which 
is exhaled from it. It is in direct contact with the ingesta. The liquid 
which it secretes has a chemical and also a dynamical relation with 
the ingesta, since its action changes their composition, and they are 
divided into two parts, one of which, the chyle (chylas), serves for 
nutrition, while the other, the fecal matter (faces), being useless, is ex- 
pelled from the body. The chyle in its turn is so modified that it enters 
into the absorbing vessels which exist in this tissue. 

The differences in this membrane relate principally : 

1st. To its thickness. 

2d. To its vascularity. 

3d. To its color, which depends on the number of its vessels. 

4th. To its solidity. 

5 th. To its extent, compared with the other membranes. 

6th. To the presence or absence of prolongations and folds which 
project within it and vary in size, the former of which are called valves, 
the others villosities. 

7th. To the nature of its surface, which is smooth or corrugated, 
and which depends on the preceding circumstance. 

8th. To the number of the muciparous glands. 

9th. To their size. 

10th. To their situation and arrangement. 

We may mention as a general law that the development of the 
inequalities on the inner face is inversely as that of the muciparous 
follicles, or still more generally that the prominences are inversely as 
the depressions ; that the first are more distinct, the more nutrition there 
is in the contents of the intestinal canal, and that the cavities are more 
marked, the greater the quantity of fecal matter in the canal. 

Considered from th% commencement of the stomach to the extremity 
of the intestinal canal, the general character of this membrane is that 
it is perforated by very numerous small openings, which are the ori- 

(1) F. Glisson, De ventriculo et intestinie, London, 1676. 
Vol. III. 26 



198 DESCIUPT1VE ANATOMY. 

fices of single minute glands, and which are arranged very com- 
pactly.(l) 

On its surface is a second membrane termed the nervous, or rather 
the cellular coat (tunica nervea, cellulosa). 

This membrane is only condensed cellular tissue, in which the 
largest trunks of the vessels and nerves are distributed before arriving 
at the mucous membrane. 

It contributes much to determine the form of the intestinal canal 
and of its folds. 

The most external membrane is the muscular tunic (tunica muscu 
losa.) 

This membrane is composed in every part by several, at least two, 
superimposed layers, situated one above the other, and separated only 
by a very thin layer of mucous tissue. 

The external layer is generally composed of longitudinal fibres, 
which are parallel to the axis of the intestinal canal and of the body. 
it is thinner than the internal, and it is extended on the intestine lesw 
uniformly. 

The internal, on the contrary, is composed of circular fibres, is 
stronger than the external, and completely surrounds the intestinal 
tube. 

The differences presented by this muscular tunic in the different 
regions of the alimentary canal relate . 

1st. To the relation between it and the mind, according as its mo- 
tions are voluntary or involuntary ; in most of its extent these are 
involuntary ; they, however, arc voluntary at its upper and lower part 

2d. To its thickness and strength. 

3d. To its more or less complex texture 

4th. To its color. 

5th. To its attachments, according as it is inserted in the bones or 
connected with the adjacent parts by mucous tissue. 

Besides these three layers there are also two others which are not 
so generally distributed : one resembles the epidermis, and covers the 
inner membrane ; the other is given off by the peritoneum, and enve- 
lops the external tunic. 

The most general character of the glandular appendages of the 
alimentary canal is, that these parts, except the spleen, are prolonga- 
tions of the mucous membrane and of the cellular tunic, each of which 
ramifies like a tree. They differ then from the muciparous glands on 
the external face of the villous tunic, because they are rather more 
distinct and are more concentrated in some parts of the alimentary 
canal 

(1) Galeati, Dc tunica intesivnorum cribrosa; in id*: Comrn. Bonon., vol. i.— 
Duvemey, (Euvres anatomiques, vol. i., |>. 480.— A. Meckel, Sua /.j structure •/> '■< 
membrane muqucust; dc* intestine dans Vhomme tt dam quelquee animaux ,■ in the 
Joum. compl. <"/<.> n med , -.<A. vii , p 209. 



OF THE DIGESTIVE SYSTEM. 199 

ARTICLE FIRST 

UPPKR PORTION OP THE ALIMENTARY CANAL. 

§ 2043 The upper portion of the alimentary canal may be subdi- 
vided into two regions, a cephalic and a cervical region 

I. CETHALIC PORTION OF THE ALIMENTARY CANAL 

§ 2044. The cephalic portion of the alimentary canal comprehends 
the cavity of the mouth and the parts within it. 

A, ORAL CAVITY GENERALLY. 
I PERFECT STATE. 

§ 2045. The oral cavity (cavum oris) occupies the lower part of 
the face It extends backward to the fauces and forward to the lips, 
by which it is continuous with the face. It is separated from the 
nasal fossae above by the bony palate (palatum osseum, s. durum), and 
backward by the soft palate (palatum molle, s. velum palati) At its 
base is the tongue, and on its sides the lower jaw, the zygomatic arch, 
and the muscles, some of which are attached to these bones, others to 
other pieces of bone, and several of which also go to the mouth. 
' As the oral cavity is circumscribed by muscles and by bones which 
are movably articulated with each other, its form varies, although in 
general it is rounded and oblong. The alveolar portion of the upper 
and lower maxillary bones, together with the teeth which are inserted 
there, divide it into two halves, an anterior, which is smaller, and which 
may be called the vestibule of the oral cavity, and the posterior, which 
is larger. The first is included between the alveolar processes and 
the lips ; the second is situated behind the alveolar arches. These 
two halves are perfectly separated from each other when the jaws are 
closed by the two rows of teeth which touch and fit each other from 
before backward. When perfectly at rest the posterior half contains 
the tongue and receives the excretory ducts of the inferior salivary 
glands, while those of the superior open into the anterior half. The 
oral cavity is covered on the outside by the common integuments, below 
which are the bones and muscles, then the buccal membrane (mem- 
brana oris), which envelopes every part of it. 

The buccal membrane in fact begins at the upper part of the ex- 
ternal faces of the lips, where the skin suddenly becomes softer, thinner, 
and redder 



200 DBSORIPTITE ANATOMY. 

It lines all the parts which circumscribe the cavity of the mouth, 
so that it perfectly closes the openings in the bony portion of the 
palate, the anterior and posterior palatine foramina. Around the 
alveoli it is uninterruptedly continuous with the membrane which 
covers them. 

It forms folds in several places. Four of these folds are situated on 
the median line. The two most anterior exist between the centre of 
the anterior faces of the two maxillary bones and the upper and 
lower lips. They are both termed the frena of the lips {frenu- 
lum labii superioris et inferioris) . The upper is much mor» distinct 
than the lower, which generally is hardly visible. The third is si- 
tuated between the posterior face of the lower jaw and the anterior 
part of the inferior face of the tongue ; it is called the frenum of the 
tongue {frenulum linguae). 

When too long or too short it is equally unfavorable to deglutition 
and speaking. 

The fourth extends from the posterior extremity of the upper face of 
the tongue to the middle of the anterior face of the epiglottis. 

The buccal membrane also forms : 

1st. Two lateral folds, which extend from the upper face of the 
tongue to the edges of the epiglottis, where they terminate. 

2d. Two lateral folds, situated on the anterior part, which extend 
from the alveolar edge of the two jaws to the inner face of the ramus 
of the lower jaw. 

3d. Two other lateral folds, which cover the two arches of the soft 
palate. 

Of these folds the most remarkable are those on the median line, as 
they make a part of the septum which extends all along the body. 

The texture of the buccal membrane is not the same in every part. 
It however always presents two general characters : 

1st. It is covered in every part by a soft, thick, and moist epi- 
dermis. 

2d. It presents almost in every part single and large muciparous 
glands. 

II. DIFFERENCES DEPENDENT ON DEVELOPMENT. 

§ 2046. The form of the oral cavity changes remarkably. In the 
early periods of life it is proportionally shorter from before backward, 
especially at its lower part, than when the subject is fully grown. At 
this time the lips do not exist, so that the oral cavity is uninterruptedly 
continuous with the face, and its roof, the palate, not being closed, it is 
blended with the nasal fossae, toward the upper part of which is the 
tongue, then proportionally very large. This horizontal septum is 
gradually developed from before backward by the union on the median 
line of the palatine portions of the superior maxillary and the palatine 
bones, and also the soft palate on each side This union is rarely 



OF THE DIGESTIVE SYSTEM. 201 

perfect before the third month of fetal existence. The soft palate is 
perfect on the median line even before its two lateral parts are tho- 
roughly united posteriorly, and the uvula descends from their centre 
between them as an entirely distinct and separate appendage. This 
soft palate is at first very broad, presents no appearance of an appen- 
dage, and is divided in its whole extent into two lateral halves. This 
division soon disappears, and at the same time the two lateral halves 
of the soft palate approach each other still nearer, and thus push the 
uvula a little forward, so that it covers the small fissure still existing 
in the anterior region of the palate. At this time its upper part is 
united to the two lateral halves, and the inferior passes downward a 
little below it. Finally the two halves of the soft palate completely 
unite with each other and with the uvula, and the formation is com- 
pleted by the gradual prolongation of the latter. The perfect union of 
the uvula with the soft palate occurs at the middle or end of the fourth 
month of pregnancy. The uvula, however, until the end of the fifth 
month continues to be bifurcated, compared with its state in the adult, 
although it is united on each side with the soft palate, so that perhaps 
this period of its development is frequently extended beyond the usual 
time, although terminated before the end of gestation. 

HI. ABNORMAL STATE. 

§ 2047. The most remarkable abnormal state of the cavity of the 
mouth is when its primitive formation continues, that is, when it com- 
municates with the face and nasal fossae, and the primitive fissures are 
not obliterated. This state of the upper lip is termed hare-lip, and that 
of the arch of the palate is termed fissure of the palate.(l) Generally 
then the solution of continuity in the lip or palate, excepting in the 
uvula, does not correspond to the median line, but occurs on one of the 
two sides, since it is situated also like the fissures by which the lips 
communicated primitively with the face. Farther, in the simple fissure 
of the palate we generally remark that the anterior and intermaxillary 
portion of the upper maxillary bone on one side is separated from the 
posterior : at least the solution of continuity is rarely situated on the 
median line, and the intermaxillary bones are seldom attached each to 
the corresponding maxillary bone, and the two maxillary bones with 
the palatine bones are not often separated symmetrically from each 
other and from the septum of the nasal fossae.(2) The mode in which 
the uvula is developed explains why fissures in it are situated on the 
median line. 



(1) Sandifert, De labio leporino congenilo, duplici et complicate) ; in the Obt>\ anat. 
pathol., book iv., ch. iii. — Tenon, Sur quelques vices de la voutc palatale ; in his 
Mem. ct obs. sur I'anatomie, Paris, 1816, p. 295. 

(2) Tonon, loc. cit., obs. i. 



202 DES0*IPT1V.E ANATOMY 

It is curious that however great this deviation of formation, it some- 
times disappears at a more advanced period, and assumes the normal 
conditions of the regular type ; the bony palate increases either alone 
or after the hare-lip is united, and the space between the oral and 
nasal cavities gradually fills up. This fact supports our previous con- 
jecture that the two halves of the uvula sometimes unite in the fetus 
after the usual period of union. 

The oral cavity presents those alterations of texture observed in all 
the mucous membranes. One of the rarest anomalies of this dass is 
the development of hairs, which have been observed once on the sur- 
face of an encysted tumor in the fauces of a newly born infant.(l) 
It has been asserted that they have been seen also on the tongue (2) 



B. PARTS WHICH COMPOSE THE ORAL CAVITY. 

§ 2048. The different regions of the oral cavity are : 

1st. The lips. 

2d. The cheeks. 

3d. The palate 

We proceed to describe also : 

4 th. The tongue. 

5th. The teeth. 

6th. The oral salivary glands 

1. LIPS AND CHEEKS. 



§ 2049. The lips (labia) are prolongations which co^er the anterior 
face of the alveolar edge of the jaws, being parallel with it. Their 
loose edges which look towards each other are more or less enlarged 
and turned over, that of the lower always more than the upper. The 
opening between them is termed the mouth (os). 

The upper lip is longer and more prominent than the lower. We 
remark in it on the median line a longitudinal depression called the phil 
hum, which extends from the septum of the nose to the place where 
the skin becomes much thinner. This depression is remarkable on 
account of the space which primitively existed at the same place be- 
tween its two lateral halves. 

In the lower lip there is nothing similar, a difference which should 
be considered : 

1st. Because we know of no instance of a fissure of the lower lip. 

(H Ford, in the Med. communic, vol. i., no. 51. 

(2) Amatui? Luaitanua, Cfts mid cent , h m p 63 



OF THE DIGESTIVE SYSTEM. 203 

2d. Because the depression of the upper lip seems to depend on the 
greater extent of the superior frenum, and on the separation of the su- 
perior maxillary bones, which always continues during life. 

The places where the two lips unite are termed the angles of the 
mouth (anguli oris.) 

The lips are insensibly continuous on each side with the cheeks. 

Both regions are formed by a cutaneous, a muscular, and a mucous 
layer. 

B. MUSCLES OF THE UPS. 

§ 2050. The different changes in the form of the cavity of the 
mouth, arc produced by the action of the following muscles which 
occupy the regions of the lips, the checks, and the chin 

a. Orbicularis oris. 

(j 2051 The orbicularis oris muscle, buccal, Ch. (M. annularis, 
orbicularis oris, sphincter oris), principally forms the fleshy layer of 
the lips, surrounds the mouth, and is situated between Lhe skin and 
the mucous membrane. It is oval, thin, fiat and broad, and is formed 
of concentric fibres. The external blend insensibly with those of its 
antagonists, or are prolongations of fibres of these different muscles 
which interlace together. These external fibres, however, are distinct, 
and arc not blended. The internal form a separate order. They are 
found near the loose inner edge of the muscle and of the lips j but they 
insensibly disappear in the external fibres. 

This muscle is united more intimately with the skin than with the 
mucous membrane. It contracts and closes the mouth, and draws up 
its angles. 

b. Buccinator. 

§ 2852. The buccinator muscle, bucco-labial, Ch., is situated be- 
tween the upper and lower maxillary bones and the orbicularis oris 
muscle. It is square, broad, thin, and flat. Its fibres have generally 
a transverse direction ; the upper, however, go obliquely from above 
downward and from behind forward, the inferior proceed in the op- 
posite direction, and the central alone are straight. Its fixed points 
are the superior and the inferior maxillary bones. It arises from the 
external face of the alveolar edge of these two bones ; its attachments 
commence behind the last molar tooth, and extend to about the second 
anterior. It also arises at its posterior part from the summit of the in- 
ternal wing of the pterygoid process, and from a ligament which ex- 
tends from that point to the alveolar edge of the lower maxillary bone. 
It is blended forward with the orbicularis oris muscle The canal of 
yteno passes through it, near its anterior extremity 



204 DESCRIPTIVE ANATOMY. 

It draws the lips and the whole mouth directly backward, contracts 
the cavity of the mouth, and consequently expels the substances in 
this cavity, so that it acts in blowing, whistling, expelling liquids from 
the mouth, sucking, forming the mass of food on the tongue, and in 
swallowing. 

§ 2053. We may distinguish into upper and lower the following 
muscles which contribute to open the mouth. 

The upper are, considering them from without inward : 

c. d. Zygomatici. 

§ 2054. The zygomatici muscles, zygomato-labiaux, Ch., are two in 
number, a large and a small (JVt. zygomaticus major et minor). Both 
are elongated and thin. The large is more round than the small, and 
is also situated further outward and backward. Both arise from the 
external face of the malar bone ; sometimes, however, the small comes 
only from the external and inferior part of the orbicularis palpebrarum 
muscle, which generally sends some fibres to them. Both go ob- 
liquely from above downward, from without inward, and from behind 
forward. They blend with the orbicularis oris muscle ; the small with 
that portion of this muscle which makes part of the upper lip ; the 
large with that which extends to the angle of the mouth and to the 
lower lip. 

Sometimes the zygomaticus minor muscle is deficient ; in other cases 
its lower extremity is bifurcated ; in some subjects it does not descend 
to the orbicularis oris muscle, but terminates in the outer face of the 
levator labii superioris and the levator anguli oris muscles. 

These muscles draw the skin of the cheeks, the commissure of the 
lips, and the whole mouth, downward and outward. They conse- 
quently contribute to enlarge the mouth, particularly when they act 
on both sides at once. 

e. Levator anguli oris. 

§ 2055. The levator anguli oris muscle, petit sus-maxillo-labial, Ch. 
{M. levator anguli oris, s. caninus), is broader than the preceding, and 
is flat and elongated. It arises in the canine fossa below the infra- 
orbital - foramen, descends almost perpendicularly, becoming thicker 
and narrower, and blends in the angle of the mouth behind the zygo- 
maticus major muscle with the orbicularis oris, and still more with the 
depressor labii inferioris muscle. 

It raises the angle of the mouth and the upper lip. 

/. Levator labii superioris. 

§ 2056. The levator labii superioris muscle, moyen sus-ma.rillo 
labial, Ch., is much larger than the preceding, and partly conceals its 
upper extremity, being covered in this place by the orbicularis palpc- 



OF THE DIGESTIVE SYSTEM. 205 

brarum ; it has nearly the same form but a different direction, for it 
descends obliquely from without inward. It arises from the upper 
maxillary bone above the infra-orbitar foramen and is attached to about 
the middle of the upper lip, so that its fibres blend with those of the 
orbicularis oris, before which it descends. 
It draws the upper lip oblicp_iely upward. 

g. Anomalus faciei. 

§ 2057. Below the preceding and the levator alee nasi labiique su- 
perioris muscle we not unfrequently find a long muscle which arises 
near the canine fossa of the upper maxillary bone, and is attached 
directly above the origin of the preceding; it is termed the anomalus 
faciei by Albinus :(1) the rkomboideus by Santorini.(2) 

It assists to raise the upper lip, and wrinkles the skin 'which 
covers it. 



h. Levator aloe nasi labiique superioris. 

This muscle has already been described. 

§ 2058. The lower muscles of the mouth, considered in the same 
order as the preceding, are, the depressor anguli oris, the depressor 
labii inferioris, and the levator menti muscles. 



i. Depressor anguli oris. 

§ 2059. The depressor angidioris muscle, maxillo-labial, Ch., called 
from its form the triangidar muscle of the lips, arises from the anterior 
part of the lower edge and the anterior face of the lower maxillary 
bone. It ascends, contracting and becoming thicker towards the angle 
of the mouth, where it blends with the orbicularis oris, the zygo- 
matics major, and particularly the levator labii superioris muscle, so 
as to form with this latter a single muscle very much contracted in its 
centre, the fibres of which, however, are not interrupted by a median 
tendon. 

When the lower part of the muscle formed by the union of the le- 
vator labii superioris and the depressor anguli oris acts alone, it draws 
the angle of the mouth and the lower lip downward, as in weeping. 
This muscle also enlarges the mouth transversely by its external 
fibres. When acting alone it contributes to raise the lower jaw. 

(1) Hist, muse, p. 167. 

(2) Obs. anat., ch. i., § 25. 

Vol. III. 27 



206 DESCRIPTIVE ANATOMY 



j. Depressor labii inferioris. 



§ 2060. The depressor labii inferioris muscle, mento-labial, Ch. 
(quadratics menti), is thin and square. It is covered at its lower part 
by the preceding, and slightly above by the base of the zygomaticus 
major muscle ; it arises farther forward and lower than tho depressor 
anguli oris muscle, ascends obliquely from without inward towards the 
lower lip, interlaces and intercrosses with that of the opposite side by 
its upper and inner part, and terminates in the orbicularis oris muscle 

It draws the lower lip obliquely downward and turns it over. 

This muscle and the preceding generally blend with the upper part 
of the platysma myoides muscle. 

k. Levator menti. 

§ 2061. The levator menti muscle is small, thick, semicircular, and 
unmated. It is attached on each side to the anterior face of the lower 
jaw, below the alveolar process of the canine tooth, occupies the trian- 
gular space between the two depressor muscles, and terminates in the 
skin of the chin. 

It raises the lower lip and skin of the chin. 

H, PALATE. 



§ 2062. The palate (palatum) forms the arch of the mouth, whick 
it separates from the nasal fossae. We distinguish in it two portions, 
an anterior or osseous portion, and a posterior or soft portion. 

The osseous palate is composed of the horizontal or palatine portion 
of the superior maxillary and palatine bones, and also of the mucous 
membrane extended on their surface. This membrane incloses a layer 
of muciparous glands which is much thicker and more complex than 
that of the two preceding regions. 

§ 2063. The soft palate, called also the veil of the palate (palatum 
molle, s. velum jjalalinum), forms a fold which extends obliquely from 
above downward and from before backward from the posterior edge of 
the horizontal portion of the palatine bones toward the base of the 
tongue. Its lower edge is loose, and presents in the centre a rounded 
prolongation, termed the uvula,(\) on each side of which is a fissure. 
These two fissured halves of the lower edge form the inferior arches of 
the palate (A. palatini inferiores) . The superior arches (A. palatini 

(1) Lisfranc, Considerations analomitjues, physiologiqv.es ct patlwlogi'iuc^ H I 
turtle ; in the Revue midicalc. vol xi., p. 233. 



OF THE DIGESTIVE SYSTEM, 207 

superior e.s) are situated a little above. Both are continuous on the 
median line in the uvula. 

The soft palate is formed of two layers of mucous membrane which 
cover its anterior and posterior faces, and are continuous with the pi- 
tuitary membrane, of a very dense layer of muciparous glands situated 
between the two membranes, and of several muscles which contract 
and vary the form of the isthmus of the fauces (islhmus faucium) . 

A prominence resembling a cicatrix exists along the anterior face of 
the soft palate and the greater upper part of the uvula ; this marks 
the primitive division of this part into two halves. 

B. MUSCLES OF THE SOFT PALATE. 

§ 2064. The muscles of the soft palate are distinguished into those 
which depress it and those which raise it. The first contract the isthmus 
of the fauces, the latter dilate it. 

The muscles which contract the isthmus of the fauces are situated 
in the two arches ; those which dilate it descend from the base of the 
skull and are directed from without inward. 

a. Constrictors of the isthmus of the fauces. 

§ 2065. The constrictor muscles of the isthmus of the fauces are 
two, the palato-pharyngeus and the glosso-pharyngeus muscles. 

a. Palato-pharyngeus. 

§ 2066. The palato-pharyngeus muscle or the superior constrictor 
of the isthmus of the fauces (M. palato-pharyngozus, s. constrictor 
isthmi faucium superior) arises from the upper part of the lateral wall 
of the pharynx, where its fibres blend with those of the superior and 
middle constrictors. Thence it enlarges, goes upward and inward, 
enters the soft palate, divides into an anterior and a posterior layer, 
which receive between them the levator palati mollis muscle, extends 
to the posterior extremity of the bony palate, and unites on the median 
line with that of the opposite side. 

It depresses the soft palate. 

b. Glosso-pharyngeus muscle. 

§ 2067. The glosso-pharyngeus muscle, or the inferior constrictor 
of the isthmus of the fauces (M. glosso-pharyngozus, s. constrictor 
isthmi faucium minor, s. inferior, s. proprius), a similar but much 
smaller muscle, ascends from the root of the tongue in the soft palate 
before the palato pharyngeus muscle, with which it unites and arrives 



208 DESCRIPTIVE ANATOMY. 

at the lower avch, where it joins with that of the opposite side at the. 
base of the uvula. 

It depresses the soft palate, and particularly the uvula. 

b. Muscles which dilate the isthmus of the fauces. 

§ 2068. There are two muscles also which dilate the isthmus of the 
fauces, the levator and the tensor palati mollis muscles. 

a. Levator palati mollis. 

§ 2069. The levator palati mollis muscle {M. levator palati mollis, 
s. petro-salpingo-staphy linns), petro-staphylin, Ch., is oblong and almost 
rounded ; it arises from the centre of the anterior edge of the petrous 
process, and from the osseous portion of the Eustachian tube, and also 
from the posterior part of the commencement of its cartilaginous por- 
tion, by a short and strong tendon, goes inward and downward, en- 
larges but becomes thinner, and blends with that of the opposite side ; 
it forms in the soft palate between the two layers of the palato-pha- 
ryngeus muscle an arch the convexity of which looks upward and 
the concavity downward. 

It raises the soft palate, and extends it transversely. 

b. Tensor palati mollis. 

§ 2070. The tensor palati mollis muscle, pterygostaphylin, Ch. 
(JVf. tensor palati mollis, circumjlexus palati, pienjgo-sal'pingo-staphy- 
linus), is broad, thin, and quadrilateral. It arises a little inward and 
forward from the upper extremity of the pterygoid process behind the 
pterygoid fossa on the inside of the oval foramen of the sphenoid bone ; 
it frequently comes also from a greater or less extent of the posterior 
edge of the internal layer of the pterygoid process, and from the outside 
of the cartilaginous portion of the Eustachian tube. It goes inward 
and downward and becomes a flat tendon, which turns on the hook of 
the pterygoid process, a mucous bursa existing between them ; it 
is attached by its anterior edge to the posterior edge of the palatine 
arch, and always blends with the tendon of that of the opposite side to 
form the upper part of the soft palate. 

This muscle extends the soft palate and draws it outward, and con- 
tributes, like the preceding, to dilate the isthmus of the fauces. 

c. Palato-staphylinus. 

§ 2071 . The uvula or the central portion of the palate, the base of 
which is pointed, is composed of numerous muciparous glands, which 
are every where surrounded, sometimes by one sometimes by two 



OF THE DIGESTIVE SYSTEM. 209 

muscles, termed the palato-staphylinus (M. uvulce, s. azygosuvulce), 
This muscle is always very long, and descends from the palatine spine 
and the anterior face of the tendon of the tensor palati mollis muscle. 
By contracting, it shortens the uvula. 



HI. TONGUE. 

A. NORMAL STATE. 

§ 2072. The tongue (lingua)(l) is the principal organ of taste, and 
also of speech and deglutition. 

We may consider it as the lower part of the cavity of the mouth, 
and consequently of the alimentary canal, which is considerably en- 
larged, and which from this fact projects within the cavity. 

Its form is oblong, its edges are rounded, and it gradually becomes 
thin from behind forward. 

Its posterior part is termed the root, and the anterior part the point 
or apex. It extends forward and on the sides much beyond its base of 
support, so that it is loose in these two regions, which form most of it. 
Its integuments are uninterruptedly continuous with the buccal mem- 
brane, which forms below its point a longitudinal fold of a very firm 
tissue, which is attached to the centre of. the inner face of the lower 
maxillary bone, fixes the organ more firmly to the part it occupies, 
and is termed the frc&num lingua. 

As the tongue is formed chiefly by muscles, it assists in articulation 
and deglutition, while on account of its membranes it is the organ of 
taste. 

Its base is formed posteriorly by the hyoid bone. 

a. Muscles of the tongue. 

§ 2073. The muscles of the tongue(2) may be distinguished into 
the muscles of the hyoid bone and the proper muscles of the tongue. 



(1) M. Malpighi, De lingua, Bologna, 1665. — G. Fracassati, De lingua.— L. Bel- 
lini, Gustus organon novissime defectum, Bologna, 1665. — L. Heister, De lingua 
sana el cegrota, Altdorf, 1716.— A. P. Walter, De lingua humana, Leipsic, 1724. — J. 
Reverhorst, De fabriea et usu lingua, Leyden, 1739. — Royen, De fabrica el usu 
lingua, Leyden, 1742. — J. A. Rinder, De linguae involucris, Strasburg, 1778. — 
Bauer, Sur la structure de la langue ; in the Journal compl. des sc. raid., vol. xiv., 
p. 181. — Gerdy, Discussions et propositions d'anatomie, de physiologie et de patho- 
logie, Paris, 1823, p. 19, pi. i. and ii. — Blandin, Sur la structure et les mouvemens de 
la langue ; in the Archiv. gin. de mid., vol. i., p. 437. 

(2) Isenflamm, De motu lingua, Erlangen, 1793. 



210 DESCRIPTIVE ANATOMY 

a Muscles of the hyoid bone 

1. Mylo-hyoideus. 

§ 2074. The mylo-hyoideus muscle (M. transversus mundibula', s. 
mylo-hyoideus) fills the larger anterior part of the space between the 
two halves of the lower jaw, viz., the two halves of the horizontal 
portion and the body of the hyoid bone. It is loose outward in nearly 
its whole extent, and is covered in its centre by the anterior belly of 
the digastric us muscle of the lower jaw. 

It is a triangular and thin muscle, the external convex edge of 
which arises from a corrugated line on the inner face of the horizontal 
portion of the lower jaw, and proceeds from before backward and from 
within outward. It enlarges considerably from before backward. Its 
anterior fibres are transverse. The posterior are directed from before 
backward and from without inward, and proceed toward those of the 
opposite side. It descends from without inward, and unites with the lat- 
ter on the median line, being separated from it only by a narrow tendinous 
band which extends from before backward to the single muscle formed 
by this union. It is attached by the inner portion of its posterior 
edge to the centre of the anterior face of the middle piece of the hyoid 
bone. 

This muscle supports those of the tongue, which rest on it, and also 
the sublingual gland, compresses the canal of Wharton, and the ex- 
cretory ducts of the sublingual gland, sustains these parts, and raises 
the hyoid bone. 

2. Genio-hyoideus. 

§ 2075. The genio-hyoideus muscle is situated directly above the 
centre of the preceding, next to the synonymous muscle of the opposite 
side. It has the form of a very elongated triangle, and arises from the 
upper part of the anterior face of the body of the hyoid bone, goes from 
behind forward and from below upward, gradually becomes thinner 
and rounder as it ascends, and is attached to the lower part of the in- 
ternal mental process directly above the mylo-hyoideus muscle. Its 
anterior and posterior attachments are by very short, tendinous fibres. 

It draws the hyoid bone upward and forward. When this bone is 
fixed by its depressor muscles it brings the lower jaw downward 
and backward, so that it acts like the digastricus muscle of the lower 
jaw. 

Sometimes it is deficient, or rather it is imperfectly developed, and 
is replaced by a smaller muscle, which arises from the median tendon 
of the preceding, and is attached to the digastricus muscle.(l) 

(1) Duille, Var. muse, Landshut, 1815, p 5, 



OF THE DIGESTIVE SYSTEM. 



3. Stylo-hyoideus. 



211 



§ 2076. The stylo-hyoideus muscle {M. stylo-hyoideus, s. levator 
ossis hyoidei) is thin, elongated, and rounded. It arises by a short 
tendon at about the centre of the external face of the styloid process, 
goes forward, downward, and inward, presents near its lower extremity 
a fissure for the tendon of the digastricus muscle, and is attached to 
the anterior half of the external edge of the large horn of the hyoid 
bone opposite the thyro-hyoideus muscle. 

It draws the hyoid bone upward and backward. 

<t is frequently doubled, which anomaly depends on the presence of 
a small accessory muscle. 

4. Sterno-hyoideus. 

§ 2077. The sterno-hyoideus muscle (M. depressor ossis hyoidei, s. 
sterno-hyoideus) is thin and elongated. It comes from the inner face 
of the first piece of the sternum and of that of the cartilage of the first 
rib, and sometimes also from the inner extremity of the clavicle; 
thence it goes directly upward, in its course approaching that of the 
opposite side, and becomes thicker and narrower. It is finally attached 
to the lower edge of the middle piece of the hyoid bone, directly at the 
side of the median line. 

It draws the hyoid bone downward, and as this bone is attached 
to the lower jaw, when the other is not fixed by its levator muscles, it 
is also depressed so that it acts on opening the mouth. 

Sometimes it blends below with the sterno-thyroideus muscle,(l) or 
arises from the centre of the clavicle.(2) 

5. Omo-hyoideus. 

§ 2078. The omo-hyoideus muscle, scapulohyoidien, Ch. (M. re- 
tractor ossis hyoidei, omo-hyoideus, coraco-hyoidcus), is a very long, 
thin, and digastric muscle. Its inferior belly arises from the upper edge 
of the scapula, sometimes also from the small ligament extended over 
the coracoid fissure ; goes upward and forward ; between the sterno- 
cleido-mastoideus and the scalenus anticus muscles it becomes a 
tendon whence the superior belly arises, which is attached to the 
middle piece of the hyoid bone on the outside of the preceding, and 
blends more or less with the stylo-hyoideus muscle. 

It draws the hyoid bone downward, backward, and a little to the 
side. This muscle frequently presents anomalies It is rarely entirely 



( 1 ) AlbinuB, Hist, muse, p. 202. 

(2) Kelcb, Bcytragc zurpathol Anal., Berlin, 17M, p. 32. 



212 DESCRIPTIVE ANATOMY. 

deficient . we have observed it once, on the left side, without a substi- 
tute. Its origin frequently varies. Sometimes the inferior belly is 
broader, so that it extends to the upper angle of the scapula.(l) 
Sometimes it arises from the clavicle,(2) and it is then unusually 
short. In some subjects the lower belly is divided into two heads, to 
winch its simple enlargement is an approximation. (3) One of these 
heads is sometimes attached to the clavicle. (4) In some cases it 
unites with the sterno-thyroideus muscle by its superior belly or by 
a special head. (5) More rarely it is not inserted in the hyoid bone 
but in the transverse process of the sixth(6) or second ? cervical(7) ver- 
tebra. 

b. Proper muscles of the tongue. 
1. Genio-glossus muscle. 

§ 2079. The genio-glossus muscle (M. exptdsor, attrahens lingua, 
s. genio-glossus), the largest of all the muscles of the tongue, arises 
from the lower jaw by tendinous fibres which are fhserted directly 
above the genio-hyoideus muscle. It is situated against that of the 
opposite side, which it does not leave because its direction is that of the 
median line ; it goes backward, enlarges much like a fan, and forms 
the greater inner part of the tongue the whole length of this organ. It 
also gives off some fibres which go outward, pass on the following 
muscle, sends several to the upper part of the pharynx, and furnishes 
a few to the upper horn of the hyoid bone and the epiglottis. 

It brings the tongue, the hyoid bone and the pharynx forward. 

2. Hyo-glossus. 

§ 2080. The hyo-glossus muscle (M. depressor linguae, s. hyo- 
glossus, s. basiocerato-chondro-glossus) is thin, and has a long square 
form. It arises from the outer part of the body of the bone, from the 
external edge of its great horn, and from the summit of the small 
horn, ascends toward the lateral part of the tongue, and contributes 
to form it. 

It draws the tongue downward. 

(1) Albinus, Hist, muse, p. 200. 

(2) Albinus, loc. cit., p. 201. 

(3) Duille, loc. cit., p. 11. 

(4) Kelch, loc. cit., p. 31.~Sels, De muse, variet., Berlin, p. 6. 

(5) feels, loc. cit., p. 5. 

(6) Kelch, loc. cit., p. 32. 

(7) Sels, loc. cit , p. 4, 5. 



HE DIGESTIVE SYSTEM. 213 



3. Stylo-glossus. 

§2081. The stylo-glossus muscle (M. retractor lingua; } s. stylo- 
glossus), the shortest of the small muscles which come from the hyoid 
bone, arises directly from its summit and also from the upper part of 
its circumference, and arrives at the root of the tongue, in which it 
expands like a fan to its point, interlacing more or less with the hyo- 
glossus and the genio-glossus muscles. 

It draws the tongue obliquely backward to its side, and enlarges it 
when it acts with its synonymous muscle. 

We have once found it double on both sides. 



4. Lingualis. 

§ 2082. The lingualis muscle is thin and narrow. It extends from 
before backward the whole length of the tongue, and interlaces prin- 
cipally with the hyo-glossus and the genio-glossus muscles. 

It shortens the tongue, and carries its point backward. (1) 



(1) Gcrdy has described better than any one before him the lingual portion of the 
special muscles of the tongue, and has followed them through its whole extent. His 
conclusions are as follow : 

The tongue is composed of a membrane, a peculiar yellow tissue, a superficial 
lingual, two deep lingual, the transverse lingual, and the vertical lingual muscles, 
all of which are distinct, of the two stylo-glossi, the two hyo-glossi, the two genio- 
glossi, the two glosso-staphylini muscles, and the fasciculi of the hyo-glosso-epi- 
glossus. 

The lingual membrane is thick and cartilaginous on its lower surface, in which 
the subjacent muscular fibres arc inserted. 

The yellow tissue covers at the base of the tongue the enveloping membrane, which 
has no cartilaginous texture in this place. It adheres to the hyoid bone, to the epi- 
glottis, and" to many muscular fibres. Follicles exist within it. 

The superficial lingual muscle covers the upper face and the edges of the tongue, 
adhere3 closely to its membrane, and is attached posteriorly to the yellow tissue. Its 
fibres go forward, some on the upper face of the tongue, converging toward the 
median line, others above and below its edges to its apex. 

The deep lingual muscles are two small fasciculi situated on each side under the 
posterior two thirds of the tongue, between the hyo-glossi and the genio-glossi 
muscles. Their fibres are attached posteriorly to the yellow tissue. 

The transverse lingual muscles are situated under the superficial lingual, pass 
through the whole breadth of the tongue and between the lateral fibres of the su- 
perficial lingual muscle, which they cross at a right angle, and are attached to the 
membrane of the tongue under the edge of this organ. They are divided on the 
median line by a fibro-cellular raphe. They gradually curve more and more to- 
wards the base of the tongue. 

The vertical lingual muscles extend from the upper to the lower lingual mem- 
brane, passing through the whole thickness of the tongue and the transverse lingual 
muscles, with which they intercross. They curve and become more and more 
oblique toward the base of the organ. 

The fibres of the stylo-glossi muscles blend with those of the superficial lingual 
muscle above and below the edges of the tongue, and send a transverse fasciculus 
under the yellow tissue, which unites to that of the opposite side. 

The hyo-glossi muscles arc situated between the stylo- and the genio-glossi. Their 
anterior fibres arc directed from the hyoid bone very obliquely upward and forward 

Vol. Ill 28 



214 DESCRIPTIVE ANATOMY. 



b. Envelops of the tongue.(l) 



§ 2083. The mucous membrane which covers the tongue is charac- 
terized principally by the great development of its papillary tissue, and 
by the facility with which the epidermis is detached from it. 

The dermis is united to the muscular membrane more intimately 
than with the subjacent parts in any other region of the body. 

Its upper face is extremely corrugated. The inequalities there ob- 
served are : 

1st. Folds. These folds are seen principally on the posterior part 
and on the edges of the tongue. They are generally arranged regu- 
larly, converge from without inward and from before backward, and 
are very compact. They are about half a line high and broad. The 
anterior present numerous transverse grooves. The posterior are 
smooth, and consequently their surface is less extensive than that of 
the preceding. Those at the most anterior part of the tongue are less 
regular and constant. In the middle of the back of the tongue there 
is frequently a more or less evident longitudinal depression. 

2d. Papillae. (2) The papillae of the tongue are arranged \;ery com- 
pactly, and cover almost all its dorsal face. They are insulated only 
at the root of the organ, where also they enlarge very much. 

They vary much in form, and hence have been reduced into several 
classes. 

They are generally small, thin, triangular, and terminated by a 
blunt or pointed summit. 

The latter are very much developed on the centre of the tongue for- 
ward and on the edges. They are termed the filiform 'papilla, {papilla 
filiformes). 

Others which are much larger, more distinct but fewer, do not exist 
in every part, and are enlarged at then looso extremity into a rounded 



to about the centre of the tongue. Some of the posterior rise perpendicularly to the 
base of the tongue ; others blend with those of the superficial lingual muscle on the 
edges of the organ. 

The genio-glossi muscles are situated side by side on the inside of the hyo-glossi 
and the deep lingual muscles: their fibres radiate from the malar process to t Ik; 
three posterior fourths of the tongue, on the median line, to the hyoid bone, the 
yellow tissue, and the lingual membrane. They pass from below upward through 
the transverse and the superficial lingnal muscle, and curve slightly upward and 
outward in the thickness of the tongue. 

The glosso-staphylini muscles go from the sides of the soft palate on the edgea 
of the tongue, where they blend with the superficial lingual and the stylo-glossus 
muscle. 

The hyo-glosso epiglossus is formed of small fasciculi, generally deficient in man, 
which go from the hyoid bone to the yellow tissue, others from this tissue to the 
epiglottis, others also from the epiglottis to the hyoid bone. F. T. 

(?) J. A. Rindcr, De lingua involucre, Strasburg, 1778. 

(2) Albinus, Dc diversilatc papi/larum lingua humancc ; in the Annulat. acad., 
booki., ch. xiv. — Scemmcn -ing, loc. cil., tab. i., fig. 1-3. 



OF THE DIGESTIVE SYSTEM. 215 

head, whence they are termed the conical or fungiform papillae (papil- 
la fungiformes, s. clavalw). 

We must however remark, that in this respect they are frequently 
replaced by single filiform papillae, which are longer and larger than 
the others. The fungiform papillae lead to the largest of the papillae 
of the tongue, which are situated at the base of the organ, vary 
much in number and size, and are arranged in two oblique series, 
which touch at one of their extremities, and thus form a V, the point 
of which looks backward. Their form is generally but not always 
conical, so that they enlarge considerably from their base to their ex- 
tremity. They are situated in a depression which is continuous with 
the surface of the tongue, by a sack with reversed edges. They are 
termed ihelenlicular papillas (p'apillce,truncatoz,capitatm,circumvallatoz) : 
they are from three to twenty in number. Each depression commonly 
contains only one, but sometimes three or four, although this circum- 
stance has no effect on their whole number or on their size. They are 
not arranged symmetrically, although generally there is one which 
corresponds very nearly to the median line, and forms the point of 
the V. 

This latter occupies the deepest of all the cavities, that which is 
termed the lacuna, the foramen cccaim of the tongue ; beside which 
there is another situated behind it, and which incloses no papillae. 

We have several times thought, but wrongly, that we have disco- 
vered in this foramen ccccum the excretory ducts either of the salivary 
glands or of the thyroid gland.(l) 

§ 2084. The papillae of the tongue appear to the naked eye, and 
frequently when viewed by the microscope before they are injected, 
smooth in their whole extent and single ; but when their vessels are 
injected, their surface presents several small asperities, which seem 
formed by collections of several fasciculi or filaments, placed one 
against another. This texture is more apparent in the larger and an- 
terior, than in the smaller and posterior part. 

Each filament contains at least one vessel ; and when well injected 
the whole surface of the tongue becomes red. These vessels form 
very complex arches and plexuses on the surface of the papillae, since 
they frequently anastomose, and their loose extremities incline toward 
each other. 

Each filament is also composed of a soft and whitish mass which 
probably contains nervous substance. At least some filaments of the 
glosso-pharyngeal nerve have been traced into the posterior papillae of 
the tongue, and some filaments of the lingual branch of the fifth pair 
into the others. 



(1) Coschwitz, Dc ductu saUvali novo, Hallo, 1724.— Refuted by Duvernoy (De 
ductu salivali Cosclnr., Tubingen, 1725), and l.y HallerfErp. et dub. circa ductum 
< oschw., Leyden, 1727). 



216 DESCRIPTIVE ANATOMV 

The arrangement of the vessels is more apparent in the anterior 
than in the posterior papillae of the tongue, because they inclose pro- 
portionally more mucous tissue. (1) 

§ 2085. Behind the lenticular papillae, the surface of the tongue is 
smooth, presenting only numerous muciparous glands ; its sides are also 
smooth. We only remark on the limit between them and the lower 
part of the cavity of the mouth, the orifices of the excretory canals of 
the submaxillary gland. 

§ 2086. The tongue is covered in every part, especially on its uppei 
face, by a thick, whitish and moist epidermis, (periglottis)(2), which is 
formed exactly like the papillary tissue, and which consequently pre- 
sents on its upper face numerous elevations, and on its lower face, 
which looks towards the papillae, a corresponding number of rounded 
depressions, so that at first glance it seems perforated with foramina, 
although this is not the case. 

§ 2087. We have already described the nerves of the tongue, and 
have given our reasons for thinking the lingual twig of the fifth pair 
is the principal conductor of the sensations of taste, while the hypo- 
glossal nerve should be considered as only the nerve of motion. 

Although the -tongue receives many nerves, and although its surface 
is very sensible, its substance is but slightly so. This explains how it 
can be very much" bruised, or how considerable portions of it may be 
tied, without giving rise to general nervous affections. (3) 

§ 2088. The tongue is the principal organ of taste; it acts also in 
articulation, and contributes to the first changes of the food in the ali- 
mentary canal. 

The faculty of taste resides principally at its point, next on its 
edges, finally at its base, and very slightly or not all in its centre. It 
however is not the only organ of taste, for the soft palate is sensible, at 
least to certain tastes, for instance that of bitter substances. Hence 
why the loss of the tongue is not necessarily attended with that of 
taste. 

The tongue assists also in articulation, inasmuch as several conso- 
nants hence termed lingual, are formed, or at least articulated more 
distinctly, by its motions in different directions. 

It also contributes to change the food in the mouth by carrying it to 
different parts of this cavity, so that it becomes perfectly moistened 
with the saliva, and also prevents its escape from the mouth. 

We shall return to this use of the tongue, and shall mention its part 
in deglutition when describing the pharynx. 



(1) Albinua, De fabrica papiUarum lingum humancc ; in the Annot. acad. 1. i. c. 
xv. tab. 1.— Hewson (Exp. Inq., vol. ii. p. 186. — Scemmcrring', loc. cit., tab. 1., 
fig. 5-9. 

(2) Albinus, De periglollide ct corpore rcticulari lingua: ; in the Annot. acad. 1. i. 
c. xvi. 

(3) E. Home, Obs. on the structure on the tongue, illustrated by cases in which a 
portion of that organ had been removed by ligature ; in the Phil. lr., 1805, p. 205-214. 



OF THE DIGESTIVE SYSTEM. 



217 



§ 2089. The changes in the tongue during its development are tn- 
flino- At first its proportional volume is greater than when the or- 
gamsm is perfect. It is also broader, and is attached to the lower wall 
of the cavity of the mouth in a smaller portion of its lower face, which 
resembles to a certain extent the peculiar formation of frogs. 



B. ABNORMAL STATE. 



§ 2090. Sometimes the tongue does not exist, either from primitive 
deviations of formation, or from ulcers which have destroyed ij. 

Its frenum is not unfrequently too solid, too short, or too long. It 
is rarely bifurcated at its point. 

The lenticular papillae also are rarely entirely deficient, and replaced 
only by skin destitute of papillse.(l) _ 

The excess in the size of the tongue is rarely congenital. It is ob- 
served more frequently during life after some accident, particularly 
from metastasis. 

In this case a portion of the organ may be extirpated without incon- 
venience. This phenomenon seems to affect females more frequently 
than males. 

The turning of the tongue backward, which produces suffocation by 
closing the entrance of the larynx, may be caused by its frenum being 
entirely divided. (2) 

The principal alterations of the texture of the tongue are scirrhus 
and cancer. 



IV. ORAL GLANDS. 
A. ABNORMAL STATE. 



§ 2091. The oral glands (Gl. orales) are of two kinds, the mucipa- 
rous and the salivartj glands. 

a. Muciparous Glands. 

§ 2092. The muciparous glands are distinguished into the anterior 
and the posterior. 

The anterior are more insulated and lenticular. Their greatest 
diameter is only two lines, and they arc found principally in the lips 
and cheeks, opposite the upper posterior molar teeth, between the buc- 
cal membrane and the muscles it covers. They are divided according 



(1) Louis, Memoir e physiologique et pathologique sur la langue ; in the M6m. de 
Vac. de chir. vol. v., p. 486-520. — Breidenstein, De mortis lingua, Erlangen, 1791. 

(2) Wc doubt whether death is ever produced by this cause, although travelers 
often speak of negroes swallowing their tongues. Superficial observers have been 
led into error by a phenomenon which is proved possible by Bourdon's researches, 
in giving reason to think, that the greatest effort in a robust person would cause 
death, and thus in some measure one commit suicide. (Rcchcrctes sur Ic mccanismc 
de la respiration el sur la drnj.lation dvt, sang, Paris, 1820, p. 84.) F. T. 



218 DESCRIPTIVE ANATOMl 

to their situation into labial, buccal, and molar (gl. labiates, bvccalcs, 
el molares). These latter are rarely blended in one mass, the excre- 
tory passages of which unite in one. 

The posterior are the palatine glands and the amygdala-. 

The palatine glands (gl. palatini?) form a continuous layer from 
one to two lines thick, which covers all the palatine arch and all the 
soft palate, the posterior face, of which they occupy. 

The amygdala or the tonsils (Amygdala:, s. lonsilla) are oval h< 
about six lines long, three thick and broad, whirl i exist in the soft pa- 
late between the anterior and posterior arches. The fluid they secrete 
enters the cavity of the mouth through several broad openings, situated 
on their anterior face. 



b. Salivary Glands. 

§ 2093. The three oral salivary glands (gl. salivates orales) which 
belong to the class of conglomerate glands(l) are situated around 
the cavity of the mouth and near the lower jaw. They are the pa- 
rotid, the submaxillary, and the sid)lingual glands. All secrete a pe- 
culiar fluid, the saliva,(2) which is one of the most aqueous fluids of 
the body, and contains a peculiar principle which cannot be coagulated 
by boiling, by tannin, or by the acetate of lead. We also find in it a 
white mucous substance, and the common salts of the serum of the 
blood. It is also remarkable for its great affinity for oxygen. (3) 

Beside the general characters of the class to which they belong, 
these glands also present several common peculiarities, the principal of 
which are as follow. 1. Their rounded form. 2. Their reddish co- 
lor. 3. They have no special membranous capsule, are surrounded 
only by condensed cellular tissue, and are loosely attached to the ad- 
jacent parts. 4. They are so situated that they are affected by the 
mechanical action of the muscles, and even partly by that of the lower 
jaw when it is moved. 5. The fluid they secrete possesses probablj' in 
every part the same properties. 

Notwithstanding these general points of resemblance, they differ so 
much in form, size, texture, situation, and color, that we must describe 
each of them separately. 

(1) N. Stcnon, De glandulis oris ct nupcr observalis inde prodeuntibus rasis, 
Leydcn, 1661. — A. Nuck, Sicdographia ducluum aquosorum analomc nova, Leyden, 
1690. — J. B. Siebold, Historic. Systcmatis salivalis physivlogicc ct patho/ogice consi- 
der ati, Jena, 1797. 

(2) G. T. Fischer, Diss, de saliva physiologicc ct pathologice considerala, Brcslau, 
1917. 

(3) Berzelius, Fortscrille dcr thierischen Chcmic, Nuremberg, 1815, p. 47.— John, 
Hecherchcs chimiques sur la sa/ive ct la liqueur que les ventriai/es de cerveau ren- 
f'ermrnt dans Vhydrociphak; in the Journ. cow.pl. des sc. mid., vol. vi., p. 270. 



OF THE DIGESTIVE SYSTEM. 219 



a. Parotid gland. 



§ 2094. The parotid gland (parotis),(\) is the largest oral salivary 
gland, and in the adult it usually weighs from four to five drachms. 

Its form is irregularly square. It is usually more high than broad, 
narrower from within outward than in any other direction, and its 
thickness is much less than its height and breadth. Its lower half is 
considerably thicker and broader than the upper. 

It is situated directly under the skin, before the lower half of the ex- 
ternal ear, between the space in the ascending ramus of the lower 
maxillary bone forward, and backward between the auditory foramen 
and the mastoid process of the temporal bone. 

Its upper extremity, which is also the smallest edge, extends to the 
posterior extremity of the zygomatic arch, and covers the head of the 
ascending ramus of the lower maxillary bone. Its smaller anterior 
half corresponds in its whole extent to the posterior part of the ascend- 
ing ramus of the lower maxillary bone and of the masseter muscle. 
The posterior half is- larger than the preceding, and fills the space we 
have mentioned. It covers the petrous portion and the styloid process 
of the temporal bone, also the external parts of the pterygoidei muscles 
and the upper part of those which arise from the styloid process. Pos- 
teriorly, the gland terminates by nearly a straight edge, which is, how- 
ever, slightly grooved anteriorly. Its lower extremity descends below 
the angle of the lower jaw ; it is in contact with the posterior part of 
the submaxillary gland, and with the middle tendon of the digastricus 
muscle. 

The lower straight edge descends obliquely, covers the posterior 
belly of the digastricus muscle, and also generally a small portion of 
the upper extremity of the sterno-cleido-mastoideus muscle. 

The posterior concave edge is adapted to the lower part of the car- 
tilaginous portion of the auditory passage. 

The parotid gland is formed of small, rounded, and distinct granu- 
lations. 

At about the upper extremity of the middle third of its anterior edge 
an excretory duct emerges, called the canal of Sleno (ductus Stenon- 
ianus)(2) The parietes of this passage are considerably thick in 
proportion to its capacity, and it proceeds from behind forward and 



(1) Murat, La glande parotide considcrc dans ses rapports anatomiqucs el patho- 
logiqucs, Paris, 1803. 

(2) Although this term is generally applied to the parotid canal, it is not certain 
that it was discovered by Steno, and not by Needham or Blaes.— N. Steno, Diss. 
dc glandidis oris ct nupcr obscrvalis inde prodeuntibus vasts, Leyden, 1661.— Id., 
Observ. anal, quibus varia oris, oculorum ct narium vasa describunlur, noviqve. 
saliva lacrymarumquc el mud f antes delegunlur ct novum BUsii commentum reji- 
citur. Leyden, 1662.— Needham, Dc formalu foelu, London, 1667; in the preface.— 
^•„?' aes > M™ 1 -'- an - horn, brutorumquc fabricam. diver sam ex hibenlia, Amsterdam. 
1673. 



220 DESCRIPTIVE ANATOMY. 

from without inward directly under the skin and on the masseter mus- 
cle. It is generally from three to five lines distant from the lower edge 
of the zygomatic process. The transverse facial artery and some 
twigs of the facial nerve accompany it. It passes on the anterio> 
of the masseter muscle, penetrates between the fibres of the buccinator 
muscle, and opens in the lateral walls of the cavity of the moulh 
opposite the first posterior molar tooth of the upper jaw, consequently 
before the range of the teeth. Its orifice is single, and presents a 
warty prominence. 

We not unfrequcntly find an accessory parotid gland (Gl. paroiis 
accessorial), situated more or less before the normal parotid gland, on 
the malar bone and the zygomatic arch. This gland never communi- 
cates with the proper parotid gland, and sometimes divides into two 
lobes ; it opens by a small passage into the parotid canal. It may be 
compared with the orbitar gland of several mammalia. 

b. Submaxillary gland. 

§ 2095. The submaxillary gland (Gl. maxillaris, s. stibmaxillaris)(\) 
is but half the size of the parotid gland. It has the form of a rounded 
triangle. It is thicker below than above, and is situated on a level 
with the angle of the lower jaw, between its inner face and the body 
of the hyoid bone. 

On the outside it touches the lower part of the inner face of the 
pterygoideus internus muscle. Forward it sends a small prolongation 
above the posterior edge and the posterior part of the lower face of the 
mylo-glossus muscle. It rests inward on the posterior extremity of 
the anterior belly of the digastricus muscle, posteriorly on the stylo- 
glossus muscle. 

Although this gland is much smaller than the preceding, it is, how- 
ever, composed of much larger lobes. 

The excretory duct, called the canal of Wharton (ductus Wharlon- 
ianus), arises from the anterior extremity ; its parietes are very thin in 
proportion to its diameter, and it is larger compared with the size of 
the gland than the duct of Steno. Its direction is obliquely from 
without inward and from behind forward ; it passes above the mylo- 
glossus muscle, below and on the inside of the submaxillary gland, on 
the outside of the upper edge of the hyo-glossus muscle, and terminates 
by a small verrucous prominence on the sides of the frenum of the 
tongue, consequently behind the range of the lower teeth. 

Farther inward the substance of the gland sends off a prolongation 
some lines thick, which follows the same direction, but does not extend 
so-high, passes through the inner part of the posterior extremity of the 



(1) Wharton, Adenographia, ch. xxi. — Van Home, De ductibus salivalibus disp. 
Ill, 1656, 1658. 



OF THE DIGESTIVE SYSTEM. 221 

sublingual gland, and opens at the side of the canal of Wharton, some- 
times in common with a small excretory duct which leaves this lat- 
ter gland. This" common duct is called the canal of Bartholini 
(ductus liartholinianus).(l) 



c. Sublingual gland. 

§ 2096. The sublingual gland (Gl. lingualis, s. sublingualis)(2) is 
situated before the preceding, so that the posterior extremity touches 
the anterior extremity of the latter, occupies on each side the whole 
length of the tongue, and may be found directly under the buccal mem- 
brane, through which it is easily felt, and is even visible, on account of 
its inequalities and prominences. It is situated between this mem- 
brane, the myo-glossus, the genio-glossus, the genio-hyoideus, and the 
hyo-glossus muscles. It is formed like an elongated triangle, and it 
is nearly as large as the submaxillary gland. 

It is composed of smaller lobes than the preceding, is whiter and 
harder than it, and opens not like the two glands previously described 
by one orifice, but by several, usually seven or eight ; it, however, 
forms no distinct excretory duct. We perceive these openings on the 
lower face of the cavity of the mouth on each side below and near the 
tongue. There are also several ducts from its anterior portion (ductus 
Riviniani), which unite with that of the submaxillary gland ; some- 
times one only anastomoses with a passage formed by a division of this 
latter, and thus give rise to the passage of Bartholini (§ 2095). 

§ 2097. There are in fact no other salivary glands or other pas- 
sages which carry saliva. Although several anatomists(3) have ad- 
mitted others, it has long been proved that the parts considered as 
such are simply those of the muciparous glands at the root of the 
tongue or around the larynx, or even of the veins of the back of the 
tongue. (4) 

§ 2098. The oral glands present no differences in respect to their 
development, except those generally remarked in all glands. 

(1) G. Bartholini has discovered it in the lion (De duclu salivali hactenus non 
acscrvpto observatio, Leydcn, 16S4). 

(2) A. F. Walther, Dc lingua humana novis inventis octo sublingualibus saliva 
Wis, nunc ex suis Junctionibus, glandulis sublingualibus eductis, Leipsic 1724 
— C J. Trew, Dc vasis lingua salivalibus atone sanguiferis epistola, Nuremburg-* 

(3) A'. Vater, Novus ductus salivalis, qui in lingua: superficic supcriore circa eius 
medium notabili orificio hiat, Wittembenr, 1720.— Id., Norus ductus salivalis isque 
pnccipuus in lingua excrctorius glandula insignis ad latcra linguae et sub eadem 
sttat itemque super radiccm linguce, cpiglottidem, circa glottidem super an/tcc- 
noulcas usque intra cesophagum expansw, Wittemberg-, 1721.— Id., De ductu salivali 
in lingua novitcr antehac dctccto, nunc dilucidato, confirmalo, novisque experimentist 
adductc > una ductus excretorius tonsillarum ac glandules thyreoidece, Wittemberc-, 
U-i.-L,. D. Coschwitz, De ductu salivali novo, Halle, 1724.— Id., Continuatio obscr- 
vatwnum dc ductu salivali, Halle, 1729. 

(4) Trew, loc. cit. 

Vol. III. 29 



222 DESCRIPTIVE AKATOMV. 



B. ABXOHMAL STATE. 



§ 2099. The anomalies of the oral glands, generally speaking, pre- 
sent nothing peculiar. 

Primitive deviations of formation are very rare. 

We must, however, mention as such the abnormal union of the 
parotid and submaxillary glands. 

These organs, particularly the parotid canal, are easily wounded ; 
this causes the saliva to flow outward, and thus forms salivary fistula. 

The closing of the orifice of the excretory canal of the submaxillary 
gland is often at least the cause of ranula, although this affection 
depends very frequently on a newly-formed cyst.(l) 

Simple enlargement is rare. The swelling of the parotid gland in 
inflammation is situated in the cellular tissue between its lobes. 

So too the general alterations of texture, as scirrhus and cancer, 
which are also attended with an increase of volume, generally occur 
not in the glandular tissue, but in the lymphatic glands, which are 
situated on the inside and below the salivary glands, since the glan- 
dular tissue is generally unaffected in this case. (2) 

The tumors developed in the lower jaw are also situated in the 
lymphatic glands of the neck. Sometimes we meet here, as in other 
parts of the system, accidental ossifications with formations entirely 
abnormal. (3) 

Calculous concretions are formed in the amygdalae and the salivary 
passages, especially in the excretory ducts of the submaxillary gland. 
These calculi are composed, according to Fourcroy,(4) of an animal 
matter and of phosphate of lime. If however we may judge from 
external characters, a salivary calculus described by us(5) seems more 
similar to those biliary concretions which have cholesterine for their 
base. 

The calculi developed in the amygdalae are of a dirty white color. 
The disagreeable odor which they generally possess probably de- 
pends,^) at least in great part, on the decomposition of animal 
matter which surrounds them and enters into their composition ; for 
frequently this matter alone is very disagreeable, and, like the forma- 



(1) Breschet, Considerations sur la tumeur nomnxie communiment ranulc ou 
grenouillctte ; in the Journ. univ. des sc. mid., vol. viii., p. 296. 

(2) Burns, Anatomy of the head and neck, p. 270. 

(3) Burns, loc. cit., p. 293. 

(4) Syst. des conn, chim., vol. ix., p. 312.— John has found nothing' else in two 
salivary calculi, one of which come from the tissue of the parotid gland : Chemische 
Zerlegung einer Concretion der Parotis ; in the Dcutschcs Arch, fur die Physio- 
logic, vol. iv., p. 602 : Chemische Zerlegung einer Speichelstcins ; same journal, vol. 
vi., p. 603. 

(51 Handbuch der pathologischen Anatomie, vol. ii., pt. ii., p. 467. 
(6) Burns, loc. cit., p. 265. 



OF THE DIGESTIVE SYSTEM. 2 ^3 

tion of the calculi of which we are speaking/ 1) depends on a derange- 
ment of the digestive function. 



V. TEETH. 

§ 2100. The teeth (dentes)(2) are the hardest parts of the body. 
In their chemical and physical properties they resemble the bones, but 
they differ from them in their mode of union with the body, in their 
mode of development, and in their vital phenomena. In all these res- 
pects they are more similar to the epidermoid parts, particularly the 
nails and hairs. 



A. NORMAL STATE. 

a. Perfect state. 

§ 2101. 1st. Situation. The teeth are inserted in most of their extent 
in the alveolar processes of the two jaws, which closely embrace them, 
and articulate with them by gomphosis. The portion in the alveolar 
process is termed the root (radix dentis). The rest of the tooth is not 
free. The centre, which is the smallest part, is termed the neck 
(collum, s. corona dentis), and is surrounded by the gum ; all the por- 
tion above projects, and is exposed in the cavity of the mouth ; this 
is the body or crown of the tooth (corpus, s. corona dentis). 



(1) Burns, loc. cit., p. 265. 

(2) Treatises on the teeth generally treat of their anatomy, physiology, pathology, 
and therapeutics, and differ only by speaking more at length on one of these heads. 
We mention several works almost entirely pathological, as many of them contain a 
number of special or general remarks in regard to their anatomy and physiology: 
Eustachius, De dentibus libellus, Venice, 1563. — B. Martin, Dissertation sur lea 
dents, Paris, 1679.— A. C. G. Cumme, Diss. sist. dentium historiam, Helmstadt, 
1715. — P. Fauchard, Le chirurgien dentiste, ou traiti des dents, Paris, 1728. — Le- 
cluse, Nouveaux Climens d'odontologie, Paris, 1754. — Bourdet, Recherches et obser- 
vations sur toutes les parties de I'art du dentiste, Paris, 1757. — Curtis, A treatise on 
the structure and formation of the teeth, Oxford, 1769. — P. X. de Wasserberg, 
Aphorismi anatomico-physiologici de dentibus, Vienna, 1770. — J. Hunter, Natural 
history of the human teeth, London, 1778.— H. G. Courtois, Le dentiste observateur, 
Paris, 1775. — Broussonet, Considerations sur les dents en gintral et sur les organea 
qui en tiennent lieu ; in the Mem. de Vac. des sc, 1787, p. 550. — A. G. Berger, Diss, 
de dentibus, Kiel, 1788.— S. H. Bring, Observationes tn hodiernam de dentibus, 
prcecipue hominum, doctrinam, Lund, 1793.— P. Hirsch, Praktische Bemerkungen 
titer die Zahnc, Jena, 1801.— R. Blake, Essay on the structure and formation of the 
teeth in man and various animals, Dublin, 1801.— J. Fox, Hist. nat. et maladies des 
dents de Vesp. humaine, Paris, 1821.— A. Serres, Essai sur t'anatomie et la phsio- 
logic des dents, ou nouvelle the'orie de la dentition, Paris, 1817.— F. Lavagna, Espe- 
rienzc e rifiessioni sopra la carie dei denti, Genes, 1821.— Heilbronn, Diss, de denti- 
bus, Berlin, 1821.— C. G. Kaathovcr, De dentium formatione atone natura, Leyden, 
1821.— J. Lemaire, Traitt sur les dents, Paris, 1822. 



224 DESCRIPTIVE ANATOMY. 

The root and neck of the teeth are covered with a thin membrane ; 
this is continuous below with a nervous and vascular tissue which 
fills the cavity of the tooth, and above with the gum ; it is termed the 
dentar periosteum, although the history of dentition seems to demon- 
strate that its relations with the teeth are not the same as those be- 
tween the periosteum and the bones. 

The alveolar processes are also covered by a fibrous and thick mem- 
brane, which in the normal state does not unite with the preceding, 
but is continuous with the upper part of the gum, and is termed the 
alveolar periosteum. 

The gums (gengivce) are a firm, resisting cellular tissue about half 
a line thick, which adhere intimately with the buccal membrane, and 
receive but few vessels or nerves. They cover the neck of the teeth, 
and also the two faces of the alveolar edges of the jaws, and furnish 
thin prolongations which extend between each two teeth, from the 
anterior to the posterior face. 

The teeth of each jaw collectively form an arch which is concave 
backward and convex forward. 

They are generally arranged very compactly, and arc placed at 
equal distances from each other. The upper and the lower touch at 
their summits. The arch formed by the upper teeth is a little longer 
than the other. Hence the upper teeth slightly project outward, and 
the anterior, which are thinner, cover the others. The posterior and 
inferior teeth have their summits slightly inclined inward, while those 
of the upper are turned more directly downward. 

2d. Form. All the teeth are more or less elongated ; their lower 
extremity is slightly pointed, and there presents a small opening which 
leads into the cavity of the tooth (cavum dentis). This cavity extends 
from the summit of the roots to the crown, and is very narrow in pro- 
portion to its length, represents the form of the tooth, and lodges its 
vessels and nerves, which are connected by cellular substance. 

3d. Number. The number of the teeth is the same in the two jaws, 
on the two sides, and in the two sexes. In a well developed man 
there are thirty-two. 

4th. Texture. The tissue of the teeth is very hard and solid. They 
are composed of two substances, the osseous substance and ihe enamel. 

§ 2102. The osseous substance or the ivory forms the largest part of 
the tooth, the root, the neck, and almost all the crown. It conse- 
quently represents the form of the whole tooth. Its hardness, which 
exceeds that of the bones, depends upon its mechanical arrangement 
and on its chemical composition. In fact it contains no cellules. 
We perceive in it but not very clearly only longitudinal layers, 
situated one upon another from without inward, and it contains 
more of lime than the other bones. Berzelius asserts(l) that one 



(1) Gchlen, Journ. fur die Chimic und Phys., vol. iii., part i., p. 19. 



OF THE DIGESTIVE SYSTEM . 225 

hundred parts of this substance contain 51.04 of phosphate of lime ; 
2.00 of fluate of lime ; 11.30 of carbonate of lime ; 1.16 of phosphate 
of magnesia ; 1.20 of soda ; and an indeterminate quantity of hydro- 
chlorate of soda. Pepys states that they contain 0.64 of phosphate of 
lime; 0.6 of the carbonate; 0.20 of gelatine; and 0.10 of water, in- 
cluding the loss.(l) 

§2103. The enamel (substantia vitrea) (2) is milk white, brilliant, 
semitransparent, and still harder and firmer than the osseous substance. 
It covers all the crown of the tooth, is molded exactly upon it, and 
preserves all the inequalities of its masticating surface, where it is 
thickest. It gradually grows thinner towards the neck. It is com- 
posed of oblique, undulating, serrated bands, concave upward, convex 
downward, which are arranged compactly from above downward, and 
exactly fit to each other. (3) 

The enamel contains still more of earthy salts than the osseous sub- 
stance. We find in it, according to Morichini :(4) 0.33 of lime ; 0.09 
of magnesia ; 0.05 of alumina ; 0.22 of fluoric and phosphoric acids ; 
0.01 of carbonic acid; and 0.30 of animal substance. 

According to Hatchett(5) it contains very little of gelatine, and is 
mostly formed of phosphate of lime. 

Foucroy and Vauquelin(6) state that it is composed of 72.90 of 
phosphate of lime, and 27.10 of gelatine and water. 

Pepys asserts(7) that it is formed of 0.78 of phosphate of lime ; 0.60 
of the carbonate ; and 0.16 of water. 

Finally, Berzelius(S) mentions as its component parts: 85.3 of the 
phosphate; 3.3 of the fluate ; 8.0 of the carbonate of lime ; 1.5 of the 
phosphate of magnesia ; and 2.0 of animal substance and water. 

§ 2104. The vessels and nerves of the teeth are proportionally very 
large. The first arise from the internal maxillary artery ; the nerves 
come from the second and third branch of the trifacial nerve, penetrate 
through the openings at the summit of the roots, correspond perfectly 
to them in number, descends into the cavity of the tooth, where 
united by cellular tissue, they form the nucleus or pulp of the tooth 
(pulpa, s. nucleus). These nerves enlarge near the neck of the tooth 



(1) Fox, loc. cit. 

(2) Ludwig-, De cor t ice dentium, Lcipsie, 1753.— Schreger, Uber den Zahn- 
schmch ; in Rosenmuller and Isenflamm, Bcytragc zur Zcrgliederuneskunst vol 
i., part i. ° 

(3) Cumme, loc. cit., p. 9.— Schreg-er, loc. cit. 

(1) Analisi dello smalto di un dente di clef ante c dci denii umani ; in the Memoirc 
della socicta italiana, vol. x., pt. i.. p. 162 ; vol. xii., pt. ii., n. 73 

(5) Phil, trans., 1799. ,F 

(6) Mem. de I'lnslitut., vol. ii., p. 283.— Annates de chim., vol. Iv r> 265 • vol 
Ira., p. 37. •> i • > • 

(7) laoc. cit. 

(8) Gehlcn, Journ.fur phys. und Chem., vol. iii., part i., p. 27. 



226 DESCRIPTIVE ANATOMY. 

become soft and reddish, and seem covered with a network of ves- 
sels^ 1) 

§ 2105. These characters are common to all the teeth ; but there are 
others in respect to which they differ, and hence they may be divided 
into several classes. 

They differ from each other in several respects, but principally in 
regard to : 

1st. Their situation. 

2d. Their form. 

3d. Their duration. 

4th. The period of life at which they appear. 

§ 2106. In respect to situation, the most general difference is that 
which exists between the teeth of the upper and those of the lower 
jaw. The latter differ from the former in being a little smaller, so that 
the curve represented by their union is narrower and shorter ; hence 
the upper row of teeth projects a little beyond the lower in every part. 

§ 2107. The teeth of the same jaw differ from each other in form ; 
hence their division into three classes, the incisors, the canine, and the 
molar teeth. 

§ 2108. The incisors (dentes incisivi, incisores, primores) are eight 
in number, four in each jaw, occupying the most internal and the most 
anterior part. They differ most from the others in the form of their 
crown. The latter is chisel-shaped, and becomes much thinner from 
the neck to the summit, which presents the cutting surface. The 
posterior face is very concave and the anterior is convex, but not in 
the same proportion. The incisors begin to become extremely thin 
from their centres. In the perfect state, when they have not been used 
for mastication, their edge is divided into a middle and two lateral 
small grooves ; but these grooves soon disappear, and the summit of 
the tooth then forms only a thin straight line, which extends the whole 
breadth of the crown. 

These teeth have but one root. It diminishes imperceptibly from 
the crown to its extremity. A depression not unfreq uently exists its 
whole length on each side, indicating the division of this root into two 
halves, an anterior and a posterior ; and even the summit is divided 
into two small grooves, an anterior and a posterior. 

The incisors differ from the other teeth in their direction ; they are 
situated more transversely, so that their loose face looks forward ; the 
other is turned backward, and their cutting edge extends from one side 
to the other. 

§ 2109. The incisors also differ much from each other. The dif- 
ference between the synonymous teeth of the two jaws is no where so 
striking as in them, even when they are most similar in size. Those 
of the upper jaw, however, extend half a tooth farther outward than 

(1) Serrcs, loc. cit., p. 52. 



OF THE DIGESTIVE SYSTEM. 227 

those of the lower jaw. The superior are twice as large as the in- 
ferior. 

The incisors of the lower jaw differ also from the others both in size 
and form. In fact they all have a chisel-like form, and their external 
edge is about as high as their internal. Sometimes, even, they aie 
all similar in this respect. But most commonly their external edge 
descends a little lower than the internal, and is continuous with the 
other by a rounded angle. 

The internal inferior incisors possess this form very seldom, and the 
others very generally. In the external superior incisors the internal 
edge is a little convex outwardly, and is insensibly continuous with the 
lower, although a little farther downward, so that the cutting surface 
is narrower than the greatest breadth of the tooth. 

These differences in form deserve notice, as they establish the gra- 
duah transition from the internal inferior incisors to the canine teeth 
through the medium of the others. 

In respect to the size, the inner pair of incisors in the upper jaw are 
a little and often much larger than the outer ; while in the lower jaw 
the incisors are about the same size, or the outer pair is a little larger 
than the inner. 

§ 2110. Next to the incisors come the four canine teeth (denies 
canini, ferini, ciispidati), one on each side. Their crown is much 
thicker from before backward than that of the incisors, but it does not 
diminish as rapidly from above downward ; hence why their summits 
are less cutting. This summit is also pointed, because the lower face 
does not describe a straight line, as the two lateral faces terminate 
higher than in the incisors, and as the crown of the canine teeth is as 
elevated as that of the latter, it follows that the lower face is composed 
of two parts which unite in the centre at an acute angle. Conse- 
quently the crown is more rounded and more conical ; it extends both 
inward and outward above that of the incisors. On the posterior face 
we perceive from above downward in the centre a slight prominence 
between which and the edges there is a small depression. This ar- 
rangement is more evident in the inferior than in the superior canine 
teeth. 

Of all the teeth the canine have the longest roots. These roots are 
single and pointed. We generally observe in them the groove men- 
tioned when speaking of the external incisors. 

§ 2111. In the posterior part of the jaw are the twenty molar teeth 
(denies molares), ten in each jaw, five on each side. They are similar 
to each other, and differ from the other teeth : 

1st. In the greater breadth of their triturating surface, which de- 
pends on the fact that the posterior face of the crown does not descend 
obliquely to meet the anterior, but is parallel with it. 

2d. In the square or rounded form of this surface generally. 

3d. In the considerable elevations and depressions in this triturating 
surface. 



228 DF.SCRIPTIVE anatojiv. 

4th. In the lowness of their crown. 

5th. In the division of their roots into several distinct branches, or 
at least they are much more distinct than any other teeth where this 
division is only indicated. 

§ 2112. Notwithstanding this general similarity they differ very 
much, particularly the two anterior and the three posterior. The fixst 
are termed the small molar or bicuspid teeth (molares anieriores, s. 
minores, s. bicuspidali), and the others, which are larger, the great 
molar or multicuspid {molares postcriores, s. majores, s. midticuspi- 
dati). 

§ 2113. The small molar teeth differ from the great : 

1st. By their smallness. They are at least one half smaller. 

2d. By their compression from one side to the other. 

3d. By their triturating surface, which is less uneven. 

4th. By the form of their roots. The latter are at most bicuspid, 
and even when they assume this form they are so only in the part 
farthest from their crown, that is, they never present as deep a fissure 
as- the posterior molar teeth. In most cases they are broader from 
within outward than those of the incisors and the canine teeth, arc 
terminated by a blunter summit, and their lateral grooves are more 
superficial. 

The triturating surface of the small molar teeth generally presents 
two eminences, one anterior and external, the other posterior and in- 
ternal. From this they take their name. This arrangement is more 
evident in the upper jaw, because the two eminences are there sepa- 
rated by a deep transverse groove. In the lower jaw the eminences 
of the small molar teeth are, on the contrary, united by a crest, the 
direction of which is from without inward. This difference deserves 
notice, because the canine teeth of the two jaws (§ 2110) differ from 
each other in the same manner. The external anterior eminence is 
always higher than the internal, particularly in the first small inferior 
molar tooth, where the internal is but slightly developed, and which, in 
these two respects, evidently makes the transition from the canine to 
the other molar teeth. 

But this is not true of the second small anterior molar tooth. In 
this we usually observe, behind the posterior eminence, a smaller and 
more prominent tubercle, or sometimes the posterior eminence is di- 
vided into two equal halves. At the same time the external is lower, 
the crown and the triturating surface are still more rounded, so that 
this tooth evidently makes the transition from the anterior to the pos- 
terior molar teeth ; it is also a little larger than the internal. 

The small superior molar teeth are more similar to the large than 
the inferior are, on account of the greater development of their posterior 
tubercle. 

§ 2114. The three posterior molar teeth generally present four blunt 
tubercles, two on the outside, ana two on the inside, which are sepa- 
rated by a crucial depression. But we usually observe also between 
the posterior two, on the edge of the triturating surface, a fifth, which 



OF THE DIGESTIVE SYSTEM. 229 

is smaller. These tubercles are also rough. The external prominences 
are generally the largest and most numerous, and frequently the in- 
ternal tubercle is single, especially in the last two molar teeth. The 
last great malar tooth is usually the smallest, and the first the largest. 

Most generally the roots of these molar teeth present three branches, 
into which they frequently divide near their crown. The last, it is 
true, generally has but one root, but this root is never as pointed as in 
the canine teeth and the incisors, and it always presents at least two 
very deep and very broad grooves, which indicate a tendency to divide. 
Sometimes also the other two great molar teeth have only two branches 
at their root ; but in this case one of the branches is always much 
broader than the other, and also presents a broad and deep groove. In 
some subjects this broad unmated branch bifurcates below into two 
small points. The branches of the roots of the molar teeth are usually 
more curved than the simple roots of the incisors and canine teeth ; 
they begin by separating from each other ; they then converge more 
or less at their lower extremity, where they even touch each other, 
and blend together at their summits, so that they intercept, between 
them a portion of the upper maxillary bone. 

§ 2115. The characters which we have mentioned are those by 
which we distinguish the teeth which remain in the jaws during most 
of fife. But there are other different teeth which exist but a short time, 
in youth, and are termed the deciduous, or milk teeth (dentes decidui, s. 
infantiles, s. lactei), in opposition to the first, which are termed the per- 
manent teeth (dentes permanent es). 

The teeth which appear at first do not continue during life ; many 
of them remain only till the seventh year, and at the fourteenth year 
all are replaced by new permanent corresponding teeth. 

§ 2116. The two classes of teeth differ from each other in number 
and form. 

In the first respect, we ought not to find more than two molar teeth 
in each half of the jaw, during the period of the deciduous teeth, whence 
there are only twenty deciduous teeth, while there are thirty-two per- 
manent teeth. ■ 

In respect to form, we distinguish also among the deciduous teeth, 
the incisors, the canine, and the molar teeth. The incisors and the 
canine teeth resemble the permanent teeth in form, number, and 
situation ; but all the deciduous teeth, and particularly the molar 
teeth, differ from their. corresponding permanent teeth. 

1st. Their crown is much stronger in proportion to their root. 

2d. They are less elevated. 

All do not present the same peculiarities in respect to size. The 
deciduous incisors and canine teeth are much smaller than the perma- 
nent teeth, particularly in the lower jaw. The contrary occurs in the 
molar teeth ; they come immediately after the canine teeth, the two 
small anterior molar teeth replace them, and the three molar' teeth 
behind them are permanent. Hence the small anterior molar teeth 
among the permanent teeth are those which correspond to the decidu- 

Vol. III. 30 



230 DESCRIPTIVE ANATOMY. 

ous molar teeth at least in respect to situation. But the latter are 
much larger ; they have not the same form as the small permanent 
molar teeth, for instead of being flattened from before backward, they 
are extremely broad, have a broad square crown, and also several, 
usually five tubercles, which are arranged around a very deep median 
groove. The anterior is nearly one half smaller than the posterior, 
although the posterior is almost as large as the largest of the perma- 
nent teeth. Besides, they have always at least two and usually three 
roots. Thus they correspond to the permanent small molar teeth only 
in number and situation, for in respect to size and form, that is, in two 
respects much more important than the two preceding, they are analo- 
gous to the three permanent great molar teeth. 

b. Differences depending - on development. (1) 
a. General remarks. 

§ 2117. The teeth pass through several periods, during which per- 
haps they differ more than any other part of the body. 

The history of their development presents several very curious phe- 
nomena. The most essential points to consider, are their mode of 
development, the period at which they appear, and their changes 
during life. 

1st. The teeth are developed in small rounded and close sacs, which 
adhere very closely to the gums. These sacs are composed of two 
membranes. Hunter thinks that the internal alone is vascular, while 
Black admits this only of the external; But we have ascertained 

(1) Besides the works mentioned previously, which also treat on this subject, we 
may consult the following : J. J. Rau, De or La et generatione dentium, Leyden, 1694. 
— J. A. Ungebauer, De dentition e sccundd ; in Haller, Coll. diss., vol. vi. — J. Or. Janckc, 
De ossibus mandibularum puerorum septennium, Leipsic, 1751. — B. S. Albinus, De 
dentium ortu et incremento ; in Annot. acad.. vol. ii. ch. ii., Quot denies mutct puer, 
et quos, ibid., ch. iii., De dentium tnutatione, ibid., ch. i. — Jourdain, JUssai sur la 
formation des denies comparic dvec celle des os, suivi de plusieurs experiences sur les 
os et sur les parties qui entrcnl dans leur composition, Paris, 1766. — A. A. Brunner, 
De eruptione dentium lacteorum ; in Wasserberg, Opp. min., Jb.sc. I, Francfort, 1775. 
— M. Girardi, De re anatomicd oratio, Parma, 1781, tab. i. — Andree, De prima pue- 
rorum dentitione, Leipsic, 1790. — Leveille, Mimoire sur les rapports qui existent 
entre les premieres et les secondes dents, et sur la disposition favorable de ccs dcr- 
nieres au diveloppement des deux mdchoires ; in the Mem. de la soc. mid. d'Emul., 
vol. viii., Paris, 1811. — Miel, Quelqucs idces sur Ic rapport des deux dentitions et sur 
V accroissement de la mdehoire dans I'hommc ; same journal. — Duval, Memoire sur 
la position relative del'ouveriurc externe du canal maxillaire, pour scrvir d la de- 
monstration de I' accroissement dela mdehoire infiricure, Paris, 1812. — J. F. Meckel, 
Essai sur le diveloppement des dents clicz I'hommc ; in the Journ. compl. des sc. mid., 
vol. i. p. 365. — Miel, Note sur la manicre dont les dents sortent des alviolcs el traver- 
sent les gencives ; in the Journ. de mid., vol. xxxix. p. 235.— J. E. Oudct, Observa- 
tion d'une altiralicn de la racine d'une dent canine, prisentant les caract&res exti- 
rieurs de la maladie des os, connue sous le nom de spinu veniosa, pricedie de quclques 
considerations ginirales sur la phys. denlaire ; in the Archiv. gin. de mid., vol. i., 
p. 340. — Geoffroy Saint Hilaire, Systeme dentaire des mammiferes et des oiseaux, 
embrassanl sous de nouveaux rapports les principaux fails de I' organisation den- 
taires chez I'hommc, Paris, 1824. 



OF THE DIGESTIVE 8YSTEM. 231 

from examining the human fetus, and those of animals, and Fox has 
also determined that these two membranes receive vessels ; the blood, 
however, seems to flow more abundantly to the external than to the 
internal. A serous fluid exists between these two layers, and the dis- 
tance between them is much greater the younger the fetus is, although 
the layers themselves are more difficult to demonstrate than in fetuses 
of a certain age, on account of their extreme smallness. 

The external layer is more spungy, looser, thicker, and softer, 
than the internal. It is very distinctly continuous with the gum, 
whence it is easy, in the fetus, especially during the early months of 
pregnancy, to extract the alveoli attached to the gum. 

The internal layer is harder, but thinner than the external. We can 
demonstrate that it forms a sac entirely distinct from the external and 
from the gum. Its relations with the teeth are more intimate than 
those of the external layer, for it is the proper organ of formation. 
The vessels of the teeth are distributed there much more evidently, 
and when injections succeed, it appears entirely red. 

2d. The small sacs or follicles appear very early. About the tenth 
week we observe very distinctly in each half of the two jaws, four, two 
anterior which are smaller,- and. two posterior which are larger ; they 
are arranged very compactly in pairs, but the anterior and the pos- 
terior are separated by a considerable space. At the end of the third 
month we find a third sac between the two pairs, and thus at this 
period the whole number of follicles is twenty. We generally discover 
at the end of the fourth month, a sixth, situated entirely backward, 
and which is destined for the most anterior permanent molar teeth. 

3d. At first these small sacs contain only a reddish fluid, which 
afterwards becomes yellowish white. After a certain time, at the 
fourth month of pregnancy, a small reddish and soft body rises from 
the base of the internal membrane ; this gradually becomes more con- 
sistent, and forms the germ or pulp of the tooth (pulpits dentis). Nu- 
merous vessels and nerves given orT from the base of the inner mem- 
brane, are distributed in this small body, which seems to be enveloped 
by a vascular membrane, which is difficult to be detached from its own 
proper substance. It is at first very low, is single in every part, and 
terminated by a rounded summit ; but it soon assumes the peculiar 
form of each kind of tooth, an'd presents its exact image, and is, in fact, 
the nucleus around which the tooth is molded. The latter is so 
developed that the loose portion appears first, and presents all the de- 
pressions and the eminences which exist upon it, while the rest is not 
yet formed. 

The teeth begin to ossify about the middle of pregnancy. On the 
loose face of the germ very delicate, thin, and elastic small points first 
appear ; these are primitively soft, but gradually become thicker and 
more consistent. These points are grooved and very slightly elevated. 
They are seen first on the most prominent part of the germ, and repre- 
sent the tubercles of the future tooth. One is developed on each 
prominence of the pulp of the tooth ; they gradually unite with each 



232 DESCRIPTIVE ANATOMY. 

other ; they begin to develop themselves only when a portion of the 
region of the germ corresponding to the crown is formed, and embrace 
that part of the pulp, which they cover so closely that some exertion 
is necessary to separate them. Their internal face and the external 
face of the germ are, however, perfectly smooth. The difficulty in 
separating them depends. only on the exact manner in which they are 
fitted to the latter, since by removing one scale, we can extract the 
whole germ through the space thus formed. Hence, it is very probable 
that there is no organic attachment between the pulp and the osseous 
substance, so that these two parts of the tooth are united by vessels, 
by cellular tissue, or by some other analogous substance. But it is 
very curious that the germ is redder in the parts covered by the osseous 
substance, and that the progress of this redness is in direct ratio with 
that of ossification. 

The points soon enlarge, so that they arc much thicker in the parts 
first developed, that is, on the triturating surface. They become much 
thinner posteriori}', where they are much softer. The crown gradu- 
ally enlarges, and its development is finally completed. Its lower ex- 
tremity contracts and becomes the neck of the tooth. The roots are 
prolongations of the crown, in forming which the germ follows pre- 
cisely the same course as in giving rise to the latter. The number of 
the roots, even when the germ has formed only the crown of the tooth, 
is indicated by that of the distinct branches given off by its vessels. 

The osseous substance forms from without inward, so that the small 
tubercles which first appear are also the parts which always remain 
exposed, and the triturating surface, like the existing portion of the 
tooth, has already its normal volume, while it is still very thin, and its 
internal cavity is very large. This phenomenon demonstrates, un- 
doubtedly, that the bony portion of the tooth- is not formed by the inner 
face of the capsule, but by the external face of the germ, since if this 
were not true, the opposite arrangement would exist. This osseous 
portion gradually thickens, and the pulp and the dental cavity diminish 
in the same ratio, although we cannot suppose that the germ ossifies. 

Shortly after the development of the osseous points, or during their 
formation, the secretion of the enamel commences, by the inner face of 
the inner fold which surrounds the crown of the tooth, so as to be per- 
fectly molded upon its prominences and depressions. The fluid ex- 
haled by this membrane deposits the enamel on the osseous substance, 
which is so soft, and adheres so slighthy to this latter in the full grown 
fetus, that they may be very easily separated. It can be detached 
also, even in the perfect state, from the influence of certain causes, 
among others, by the action of heat. We discover no special gland 
for its secretion. It may, however, be easily separated from the pro- 
longations of the internal layer. These prolongations which arise 
from the portion of the capsule attached to the germ, arc at first very 
thick and moist ; they gradually disappear as the enamel forms, so 
that we may consider them as the germ of this production, and similar 



OF THE DIGESTIVE SYSTEM. 233 

to that which arises from the bottom of the capsule to secrete the 
osseous substance of the tooth. 

The different kinds of teeth do not ossify after the same type in re- 
spect to time and form. The internal incisors are the first, and the 
posterior molar teeth the last to appear. In regard to the intermediate 
teeth, the deciduous teeth differ from the permanent teeth. The in- 
cisors and the canine teeth arise by one small point, and the molar 
teeth by several, viz. the small by two, and the large by four or five. 
Each point always possesses a thin triangular form on its appearance, 
which is the constant form of the crown of the canine tooth. In the 
incisor and molar teeth these points extend, and those of the incisor 
teeth present two small accessory points, which do not arise by special 
nuclei. Among the different points of the canine teeth the external 
and the anterior are developed the first, and next the internal. In the 
large posterior molar teeth the anterior external is first seen, then the 
anterior internal, and the two points of the first posterior form in the 
same order. The different points unite according to the same law, so 
that judging from their development, the large molar teeth seem to be 
formed by two smaller teeth. 

The inferior arise or are developed before the superior. The points 
of the anterior deciduous molar tooth are already united to the lower 
jaw in the full grown fetus, while this is not the case in the upper jaw. 
In one case where the first inferior permanent molar tooth presented 
five osseous points, there were only three in the superior. 

§ 2118. When is the formation of the tooth completed? It is not 
certainly when it appears, since the tooth cuts through the gum before 
it is perfectly developed ; but we have now to inquire if the tooth 
undergoes any other internal changes after the root' is perfectly 
formed. 

Those who maintain this fact adduce the following arguments : 

1st. The change in the tooth in animals fed with madder. 

2d. The projection of one tooth above the rest, when the corres- 
ponding tooth in the opposite jaw is extracted. 

3d. The union of fractured teeth. 

The following arguments have been adduced in favor of the conti- 
nual reproduction of the enamel : 

4th. The pathological changes in this substance, particularly the 
black spots, which do not reappear after being removed until a new 
disease supervenes.(l) 

5th. The duration of the enamel, which cannot be explained when 
we consider the continual friction of the teeth, except by admitting it 
is constantly forming. (2) 

The following arc objections to these different arguments : 



(1) Hiracb, loc. cit., p. 17. 

(2) Ibid. 



234 DESCRIPTIVE ANATOMY. 

let. The coloring of the bones generally by madder does not prove 
that their substance is constantly reproduced.(l) 

2d. Probably we have less right to admit an increase in the size of 
the tooth than its expulsion from the alveolar process. Beside the 
phenomenon to which it alludes does not occur in man or in most 
mammalia, although observed in some of them, particularly the 
gnawers, (2) the teeth of which project after being extracted or cut off. 

3d. The union of fractures of the teeth does not prove that their 
substance is continually reproduced, but only that in some cases the 
germ of the tooth can restore a fractured part by a process analogous 
to that, when at the commencement it secretes the osseous substance 
in every part. 

4th. It is nowhere proved that the enamel is formed again in the 
pathological cases adduced. 

5th. The duration of the enamel depends on its solidity. 

Thus the arguments in support of the continual formation of the 
teeth in general, and particularly of the enamel, are by no means con- 
clusive. On the contrary the second fact contradicts it. Beside the 
mode in which the enamel is developed does not admit this theory. 

§ 2119. Beside the whole duration of pregnancy, a long time ad- 
vances, usually six months after birth, before the teeth appear, at least 
externally. 

During this period we find in the place afterward occupied by them, 
a very hard and in fact a cartilaginous mass, which projects and 
presents numerous grooves some lines deep and entirely different from 
the gum ; this arises above the surface of the alveolar edges and 
fulfills the function of the teeth, that is, it serves principally to retain 
the nipple. 

This substance may be called the dental cartilage (cariilago den- 
talis). It is worthy of notice as analogous to the horny beak of birds 
and reptiles. It disappears as the teeth are developed and perforate 
the gum. 

We discover in this substance, particularly in the region of the molar 
teeth and on its inner and concave side, several follicles of different 
sizes, containing a shining and yellowish substance ; these are at most 
but half a line in diameter, and apparently have no external orifice. 
Serres first mentions these follicles. (3) He thinks that they soften the 
gum of the child before the teeth appear, and afterwards secrete the 
tartar of the teeth. We however have never observed them until the 
period when the teeth appear, so that hitherto we have considered 



(L) B. Gibson, On the efect of madder-root on the bones of animals ; in the Mem. 
of the literary society of Manchester, 2d series, vol. i., p. 146-164. 

(2) Lavagna, Osservaz. sulla carie dei denti, Genoa, 1812. — Oudet, Experiences 
aur V accroissement continu et la reproduction des dents chez les lapins, considirtcs 
sous le rapport de leur application a V etude de V organisation des dents humaines ; 
in the Journ. dephys. exptr., vol. iv., p. 70. 

(3) hoc. city?. 28-33, pi. 4, f. 6. 



OF THE DIGESTIVE SYSTEM. 235 

them simply as new formations, caused by the irritation of the teeth 
which are soon to appear ; they probably do not differ in their nature 
from abscesses. 

§ 2120. The triturating surface of the permanent teeth, like that of 
the deciduous teeth, changes more or less during life. The enamel is 
gradually used by friction so that the osseous substance is exposed, 
and the triturating substance, formed at first entirely of enamel, pre- 
sents only a layer of osseous substance when the cutting edges and 
the pointed summits of the crowns are blunted. When the tooth is 
still more worn, so that the osseous substance is destroyed to the 
dental cavity and the latter is open, there is generally formed in the 
same proportion at the summit of this cavity a brownish substance re- 
sembling bone, but a little softer, which closes the opening and protects 
the parts within the cavity.(l) These phenomena can also be ad- 
duced against the opinion of those who assert the continual reproduc- 
tion of the enamel. 

Nutrition however gradually declines in the teeth, and their nutri- 
tious foramina are finally obliterated. Being retained in the alveolar 
processes by no organic attachment, they become loose and fall out. 
The alveolar processes collapse and the alveolar edge entirely disap- 
pears after the gum has closed the alveolar openings. 

b. Special remarks. 

§ 2121. The different kinds of teeth do not pass through the dif- 
ferent periods generally mentioned in the same time, but very irregu- 
larly and more or less in succession. We may mention generally : 

1st. That they pass through the different periods after the same 
law, so that the germ of the tooth in which the follicle first appears is 
also the first to be developed and ossified. 

2d. That the synonymous teeth in the same jaw correspond very 
exactly in this respect. 

3d. That the lower teeth are developed before the upper, and the 
anterior before the posterior. 

4th. That the gradual development of the human teeth corresponds 
to permanent forms in the mammalia. 

1. Deciduous teeth. 

§ 2122. The -deciduous teeth, in accordance with the first law, 
appear sooner than the permanent teeth. The period at which their 
follicles are developed and the order in which these latter are seen have 

(1) Hunter, loc. cit., p. 108.— Prochaska, Obs. dc Ut-crcmcjilo dcnlium ; in the 
Annot. acad.,fasc. I. 



236 DESCRIPTIVE ANATOMY. 

already been mentioned above. The two internal follicles are those 
of the incisor teeth, and the external those of the molar teeth ; the fifth 
intermediate is that of the canine tooth. 

Ossification begins at the fifth month in the inner incisor teeth, a 
little sooner in the lower' than in the upper. Next comes the external 
incisor tooth, then the anterior molar tooth. About the end of the fifth 
month we find osseous substance in these three teeth, while only the 
germ exists in the other two. We have as yet been unable to deter- 
mine whether the canine or the posterior molar tooth is ossified first, 
because, except in one instance, we have always found these teeth 
with or without traces of the osseous germ at the same time. Pro- 
bably, however, ossification commences first in the former, not only 
because we have once found in it an osseous germ, while there was 
none in the posterior molar tooth, but because its osseous nucleus has 
always seemed to us more extensive than that of the latter, and finally 
because it is cut first. But these three reasons, particularly the last 
two, do not establish our opinion with certainty. 

At the seventh month of pregnancy all the deciduous teeth contain 
osseous nuclei.(l) 

The number and arrangement of the pieces of bone which form the 
teeth are not always exactly the same. 

Hunter(2) and Rudolphi(3) think that the incisors are composed of 
three pieces, a central and two lateral pieces, which are smaller. The 
canine teeth arise by a single osseous germ according to Hunter ; but 
Rudolphi thinks by two lateral halves. Both admit that the anterior 
molar tooth is formed of an anterior portion and of one or two posterior 
pieces, and that the posterior is formed by an anterior germ and several 
posterior nuclei. Hunter however is very brief on this subject, al- 
though he seems to speak from observation. Rudolphi's assertions 
are grounded, not on researches in regard to the development of the 
teeth in the fetus, but upon chemical experiments, having for their 
object the action of the acids on perfect teeth, which action reduces 
them to the number of pieces mentioned by this physiologist. Nume- 
rous observations on the fetus have convinced us that the canine and 
the incisor teeth are developed by a single germ, which arises at the 
centre and gradually extends to the sides. We cannot then consider 
as natural, conclusions drawn from the action of acids on perfect teeth; 
and farther, because other writers', as Albinus,(4) and Blake, (5) for- 
mally assert that the incisor and the canine teeth are developed by one 
nucleus of ossification. But the molar teeth in fact arise by several 



(1) Blake (Essai, p. 23) states only that he has found osseous substance in all the 
teeth in a fetus of eight months. 

(2) Loc. tit., p. 88. 

(3) Ueber die Zdhne ; in his Anatomisch-physiologtichc I'ntcrsuchungcn, p. 126. 

(4) De dentium ortu ct incrcmcnlo ; in the Annot. acad., book ii., ch. ii., p. 16. 

(5) Loc, tit., p. 6. 



OF THE DIGESTIVE SYSTEM. 237 

osseous nuclei, each of which corresponds perfectly to the first rudi- 
ment of a single incisor or canine tooth. 

First the anterior piece, which is the largest, appears ; this corre- 
sponds peculiarly to the incisors, and is narrower according to its 
height than it is afterwards. Next is seen the posterior piece, which 
is much smaller ; it igradually extends and unites to the other directly or 
on one of the two sides by a third which is developed at a later period. 
The second molar tooth arises by several pieces, at least three and 
generally four in number, an anterior, two lateral, and a posterior. 
The anterior piece is always larger than the others. 

All the pieces except the small one, which belongs to the posterior 
molar tooth, are usually fused at birth. 

About this period the development of the first and second incisor 
tooth is nearly equally advanced in regard to the whole crown. Next 
comes the anterior molar tooth, the crown of which has not yet how- 
ever acquired all its height. The third is the canine tooth. The 
most imperfect is the posterior molar tooth, the very thin crown of 
which presents in one or more points considerable spaces in its central 
portion, and a piece which is entirely distinct from the others. The 
posterior molar teeth of the lower jaw not unfrequently form a single 
piece in the full grown fetus. Beside the spaces . and the separation 
mentioned disappear in the two jaws in the first few months after 
birth. 

The cutting of the deciduous teeth usually commences at the be- 
ginning of the seventh month after birth. The lower internal incisors 
are generally first seen ; some weeks after, the upper internal incisors 
are cut ; one or two months afterward, the upper and lower external 
incisors ; at the end of the first year, the lower anterior molar teeth ; 
some time afterward, the upper anterior molar teeth ; at the age of 
eighteen months the inferior, and soon after the superior canine teeth ; 
toward the end of the second year, the posterior molar teeth : so that 
at the age of three years all the deciduous teeth are seen. 

The deciduous teeth receive a distinct artery, which comes from the 
dental artery, and which passes through a canal in the jaw, into which 
it enters through a special foramen . ( 1 ) 

2. Permanent teeth. 

§ 2123. The permanent teeth are developed and appear nearly in 
the same order as the deciduous teeth. They however pass through 
their periods much more slowly. 

We observe first just before the end of the first month of pregnancy 
the follicle of the anterior molar tooth. Those of the incisors do not 

(1) Scires, loc. cit.> p. 16. 
Vol II J 31 



238 DESCRIPTIVE AKAT0MY. 

form till the commencement of the eighth month ; next that of the 
canine, and next that of the middle great molar tooth. That of the 
anterior small molar tooth forms some months after birth, rarely 
before the seventh or eighth. Next appears that of the posterior 
small molar tooth, and usually at four years of age that of the third 
great molar tooth, which is situated the most posteriorly. The os- 
seous germs are visible nearly at the same time as the follicles. 

Ossification commences in the anterior great molar tooth. Usually 
the external anterior point of this tooth presents at the end of the 
last month, of pregnancy, a small osseous piece, to which four or 
five others are gradually attached separately ; these do not unite till 
the end of the first year. We however have sometimes found in a 
very krge full grown fetus five points, in fact entirely distinct from 
each other, the posterior of which was still very small. 

All the permanent teeth have not the same situation in respect to 
the deciduous teeth. The three posterior molar teeth are situated on 
the same range as these latter, but farther outward, while those which 
should be properly called the replacing teeth are included between 
them and the posterior wall of the alveolar processes, the incisors, the 
canine and the molar teeth, behind those to which they correspond. 
The follicles of the permanent teeth are at first contained in the same 
alveolar processes as the old teeth. The manner in which they are 
developed is very curious. They leave the upper and posterior part of 
the dental follicles already existing, so that they may be considered to 
a certain extent as arising from these latter by gemmation. They first 
rest directly on them, and even afterwards when they are elongated 
they communicate with them by long and thin cords. 

Our observations, however, have established that this communica- 
tion is only between the external layers of the dental follicles, that the 
internal layers are much more essential, and entirely distinct from each 
other, so that the new internal dental sac is developed in the old, be- 
tween it and the external layer, although their cavities are uncon- 
nected. If they communicate, it must have been at a very remote 
period, since we have never been able to discover it even on examining 
• the follicles of the permanent teeth when they first appear. 

The new sacs are gradually separated from the old by the formation 
of new alveolar cavities. These cavities seem at first slight depres- 
sions in the posterior wall of the old ; these depressions, like the 
follicles, are much shorter than these latter, and extend much farther 
beyond the alveolar edge than those which existed previously. A 
septum gradually aris r ^ from the base of the alveolar processes, and 
goes towards its orifice. The two alveolar processes, however, con- 
tinue to communicate by a considerable opening, through which passes 
the cord which unites the two sacs. The elongation and the thinness 
of this cord depend on the increase in the height of the jaws. 

The openings between the inoisors and the canine teeth are visible 
on the posterior face of the jaws. That of the internal incisor tooth 
corresponds to the cavity of the deciduous internal incisor tooth. That 



OP THE DIGESTIVE SYSTEM. 239 

of the external is situated between the cavity of the deciduous external 
incisor tooth and that of the deciduous canine tooth. That of the 
canine tooth is situated behind the cavity of the deciduous canine 
tooth. The communications of the anterior molar teeth with the 
cavities of the deciduous molar teeth, are not visible externally, ac- 
cording to several anatomists,(l) but exist at the bottom of those latter; 
we, however, have observed that they are situated like the first, on the 
inside, and behind the alveolar opening of the deciduous tooth, and that 
they are generally narrower than the others. (2) The follicles of the 
second and third permanent molar teeth emerge in the same manner, 
the first on the outside of the deciduous molar tooth, the other after- 
ward, on the outside of the second. The foramina of communication 
between their cavities are situated at the upper part of the septum 
which separates them. As the jaw and the deciduous teeth gradually 
arise by the development and completion of their roots, as the per- 
manent teeth which replace the latter do not increase proportionally in 
this direction, and as they are much broader than the deciduous teeth, 
it follows that they are situated lower, and also a little on the outside 
of them. The permanent internal incisor teeth are situated behind the 
internal and a part of the external deciduous teeth; the permanent ex- 
ternal teeth behind these latter and the deciduous canine teeth ; finally, 
the anterior molar teeth behind the deciduous molar teeth and between 
then roots. The crowns of the latter nearly touch the roots of the 
permanent internal incisor teeth, and the canine teeth are on the out- 
side of the row, more remote from the alveolar edge, and are carried 
farther forward than the others. 

§ 2124. At the age of six or seven years the second dentition com- 
mences ; the deciduous teeth fall out and the permanent teeth appear. 
At this time the artery of the deciduous teeth and its canal disappear 
more or less perfectly,(3) so that the dental capsules receive no more 
nutritious fluid. Usually, and in fact almost always, the permanent 
anterior molar teeth begin to appear before the time of the second 
dentition, which has deceived some writers, and led them to admit 
twenty-four deciduous teeth. Among the teeth which alone deserve 
to be called permanent teeth, the inferior internal incisor teeth usually 
appear first. Next come the superior internal, then the external ; after- 
ward, and usually at the age of from thirteen to fourteen years, and 
almost always at the same time, the canine and the middle great molar 
teeth appear ; finally, at a variable period, between sixteen and twenty 
years, and sometimes later, the last great molar teeth appear, which 
are hence called the ivisdom teeth (dentes sajnentiaz). Thus, although 
the permanent canine teeth appear much sooner than the small molar 
teeth, they however normally are cut afterward, between the appear- 
ance of these latter and the posterior molar teeth, exactly as the deci- 

(1) Albinus, loc. cit., p. 13-15.— Blake, loc. cit., p. 40.— Serres, loc. cit. p. 38, 

(2) Meckel, loc. cit. 

<3) Serres, loc. cit. p. 19. 



240 DESCRIPTIVE ANATOMY. 

duous canine teeth appear in the jaws between the two deciduous 
molar teeth. 

The order then in which the teeth arc cut, is nearly the same for the 
deciduous and the permanent teeth. 

Both resemble formations which are permanent in animals. 

The appearance of the incisors before the others deserves notice, as 
it resembles the development of the intermaxillary bone, and the cor- 
responding middle portion of the lower jaw which exist particularly 
in fishes, and more or less in all animals. The earlier development of 
the lower represents remarkably the formation of the ruminantia, and 
the regular existence of the incisors and the molar teeth without the 
canine teeth in the rodentia. 

The deciduous teeth change in certain respects before falling out. 
Their roots disappear ; they become both shorter and thinner, so that 
their inner part diminishes as they terminate more or less in a point. 

The more or less narrow canal in which the cavity of the per- 
manent tooth is first situated, gradually enlarges, as well as its orifice, 
as the tooth advances ; finally, the septum which seperates the alveolar 
process of the permanent tooth from that of the deciduous tooth, is de- 
stroyed, and the two teeth are then situated in the same cavity as they 
were originally, with this difference, however, that the permanent 
tooth, from its greater size, always penetrates partly into the alveolar 
process of the adjacent deciduous tooth. 

The destruction of the root of the deciduous tooth doubtless depends 
on the mechanical action of the permanent tooth upon it, in accordance 
with the law, that long continued pressure on a part, causes it to dis- 
appear by obstructing nutrition, or by accelerating the destructive pro- 
cess. This is proved not only by the disappearance of the deciduous 
tooth, but also by the well known fact that those temporary teeth 
which are not replaced by the permanent teeth, continue very long 
even in the adult, and sometimes even during existence.(l) Although 
the tooth which continues longer than usual often finally falls out, (2) 
we must not conclude that the permanent teeth have no effect in the 
normal state independent of their influence, but only that the decidu- 
ous teeth from their primitive destination, exist so short a time that 
this action is not absolutely necessary to determine their decay. 
Finally, the continuance of the deciduous teeth even after their vessels 
and 'nerves have completely disappeared, is favored by the adhesions 
between their root and the inner face of the alveolar process. (3) 

The permanent tooth causes the decay of the deciduous tooth prin- 
cipally by pressing upon the vessels and nerves of this latter, and like- 
wise its adhesions with the alveolar process, and destroying them. 
The destruction of the root is not indispensible, nor even constant, as 
the deciduous teeth are sometimes shed, preserving their roots entire. (4) 

(1) Hunter, loc. cit., p. 99.— Hudson, in Blake, p. 67.— Fox, loc. cit., p. 40. 

(2) Fox, loc. cit. 

(3) Serres, loc. cit., p. 97. 

(4) Idem, loc. cit., p. 102. 



OF THE DIGESTIVE SYSTEM. 241 

This is the proximate cause of the loss of the tooth, and not, as has 
been asserted, the space formed by the disappearance of the septum 
between the alveolar processes, the only effect of which space would 
be to fix the tooth less flrmly.(l) In fact, there is no space, since the 
permanent tooth, in proportion as it destroys the septum, prevents the 
space from forming', as it enters the alveolar process of the deciduous 
tooth. 

§ 2125. From our preceding remarks it follows, that the teeth re- 
semble the bones generally in their chemical composition and hardness. 
They however differ from them in these two respects : 

1st. They are harder. 

2d. Their tissue is much more solid. 

3d. They are composed of two substances. 

4th. They contain a much greater proportion of earthy salts. 

They differ also from the bones. 

5th. They are unattached in most of their extent. 

6th. In their mode of connections with the rest of the body, and in 
their relations with the germ of the tooth. 

7th. In their mode of development. 

8th. Because they do hot participate in the diseases of the osseous 
system. 

9th. They receive no vessels. 

10th. They resist much more the action of chemical agents and 
spontaneous decomposition after death. 

In all these respects, on the contrary, they are very similar to the 
epidermoid parts, which analogy is confirmed by comparative ana- 
toroy.(2) 

(1) Serrcs, loc. cit,, p. 104. 

(2) Mayer and Kathovcn arc the first who arranged the teeth as belonging to the 
horny system, which has been followed by Heusinger, but opposed by Rudolphi, but 
very wrongly. Bonn (Do conlin. membran., 1763, § 16), Walther (Physiologie, vol. 
i. p. 176), and Lavagna (/w. cit., p. 164), had already mentioned the analogy between 
the teeth and the hairs. This point of doctrine bad been carefully developed by 
Lavagna, and afterwards by Heusinger. The reasons alledged by the latter are, 1st. 
The teeth in the different mammalia present imperceptible transitions, from those 
which arc most similar to the bones, to the different parts of the horny system, par- 
ticulai ly the nails, the horns, and the hairs. 2d. The teeth of several, of the mam- 
malia hare a lamellar texture like the nails and the horns, and this texture, although 
very evident in all, sometimes seems effaced from the greater accumulation of the 
earthy salts. 3d. The development of the teeth is very similar to that of the nails 
and horns. 4th. Certain teeth are shed and reproduced, as are also the nails and the 
horns. 5th. The teeth are not nourished, they axe formed entirely of one piece, and 
the substance which forms them is not renewed. These views are in part those of 
Coiter, Herissant, Cuvier, and Serrcs. G. F. St. Hilairc has adopted them entirely. 
The tooth, he says, ti produced by ttansudation ; it is an inorganic body, anatomi- 
cally speaking, a mass composed of several layers, in which there is nothing to be 
compared with osseous tissue. But this naturalist has extended these ideas very 
much by demonstrating that we must refer the beak of birds to the formation of the 

B curious fact, and one of the highest importance, which fully justifies the 
y established between this formation and the epidermoid tissue. He advances 
also another idea, which we shall mention here briefly, although connected with im- 
portant physiological considerations, it is foreign to this work, viz. that if the teeth 
afterwards serve for mastication, it is fortunate" for those animals who possess and 



242 DESCRIPTIVE ANATOMY. 



B. ABNORMAL STATE. 

§ 2126. The teeth not unfrequently vary from the normal state ; 
and most generally present anomalies in their texture. The most fre- 
quent alterations of texture are those which relate to the period of 
development and the order in which it occurs ; next, those which relate 
to the number of the teeth. Next come the anomalies in situation and 
direction, and finally those in form, size, and continuity of tissue. 

a. Deviations of formation. 

§2127. 1st. Anomalies in the development. These are the slightest. 
Not unfrequently all the teeth, or some of them only, appear unusually 
late. This is seen particularly in the last molar teeth, in regard to 
which we should remark, that their unusually late appearance is only 
an extension of time between their appearance and that of the other 
teeth, as between the appearance of these latter compared together. 
It is less common for all or some of the teeth to appear sooner than 
usual ; sometimes, however, children are born with several teeth. It 
is curious, although the fact agrees very well with the laws and the 
other phenomena of vegetative life, that this early development 
seems evidently to be favored by the longer continuance of the fetus in 
the uterus, since in a proportionally great number of children who had 
continued in the fetal state some weeks beyond the common period, 
teetk existed at birth. 

We must mention among the anomalies in the development, the 
continuance of the deciduous teeth beyond the usual period, which 
does not necessarily oppose the appearance of the permanent teeth, 
and causes so much irregularity in their arrangement and situation, 
that we are led at first view to believe the number of the teeth to be 
increased. But the deciduous teeth frequently remain, although the 
permanent teeth do not appear, and this anomaly must even be attri- 
buted to the absence of these latter. 

Beside these differences in the development which relate to the 
quantity, there- are others dependent on the quality. Thus, sometimes 
all the lower incisor teeth appear before one of the upper is seen. It is 
much more rare that the superior incisors appear before the inferior, 
the external before the internal, the anterior molar teeth before the ex- 
ternal incisors, and the posterior before the canine teeth.(l) The rarest 
case is where the canine teeth appear before the anterior molar teeth, 

profit by them, but that when the formations of the teeth begin to appear in the fetus, 
they are real organs of the fetus ; in this sense they arise, like all the organs of sense 
to form a termination to the circulatory system of the advanced parts of the head, 
tojlimit a certain number of vascular trunks. F. T. 

(1) Blake, p. 25.— Fox, foe. cit., p. 7.— Serrcs, p. 85. 



OP THE DIGESTIVE SYSTEM. 243 

although several authors mention this as the normal order, or at least 
state it to be as frequent as that mentioned above.(l) 

2d. Anomalies in the number. These teeth which most frequently 
appear later than the common period, the posterior molar- teeth, are 
also those which are most commonly deficient. Instances, however, 
are known of the deficiency of every tooth. (2) In one subject there 
were only four permanent teeth in each jaw. In another there was 
only one incisor in the upper jaw. Sometimes the teeth have been 
entirely deficient. (3) 

It is more rare to find an excess than a deficiency of teeth. This 
anomaly, leaving out of view that which is only apparent, and which 
we have just mentioned, appears principally under two different forms. 
Sometimes the supernumerary teeth exist simultaneously with the 
others; sometimes, however, they appear after them. 

In the first case they make part of the same range with the others ; 
sometimes are found out of this range, so that when several exist they 
form a second series. They are generally situated behind the normal 
teeth, that is, the same relation exists between them and these latter 
as between the deciduous and the permanent teeth. This anomaly 
varies in the same manner as that which depends on the abnormal 
situation of the teeth in general. 

The first degree of the redundancy of the teeth is the development 
of one or more rounded eminences on the sides of the crown ; hence 
are formed what are termed the denies proliferi.(4) This anomaly 
seems to belong almost exclusively to the molar teeth, and it is curious 
as it is a greater development of one of their peculiar characters, the 
existence of several points on their crown. 

The anomaly is still greater when other smaller separate teeth exist 
on a normal tooth, and which are seemingly formed by special germs. 
In the only case of this anomaly known to us, and which existed on 
a canine tooth, there were three accessory teeth ; these small teeth 
were much smaller than the normal canine teeth, but were all formed 
after the same type ; they rested on the base of the crown and had 
the same direction. (5) 

The supernumerary teeth are observed most frequently in the upper 
jaw and forward, near the canine teeth and the incisors. This pecu- 
liarity is very remarkable, since in several animals the anterior teeth 
are more numerous in the upper than in the lower jaw. They usually 



(1) Micl, Bull, de la soc. med. d'£mul., 1817, p. 94. 

(2) Fox mentions several instances of this. 

(3) Fox. loc. cit., — Sabatier, Anat., vol. i. p. 78. 

(4) Bartholin, Hist. anat. rar., ch. i., p. 49.— Serres, loc. cit., p. 160.— Linden, 
Medic, phys., cap. xiii., art. 3.— Oudet, Bull, dc lafac. dc med., 1821, no. i., p. 369. 
— G. Saint Hilaire has described and figured one of these teeth (Syst. dentaire des 
mammif. et des oiscaux, p. 77, pi. i., fig - . 18). _ 

(5) Lemairc, Deux observations d'anatomie pathologique swr les dents; in the 
Journ. de med., vol. xxxvi., p. 252. 



244 DESCRIPTIVE ANATOMY. 

differ from all the normal teeth in form and size, being smaller and 
conical, sometimes bicuspid. When they occur at the posterior part 
of the mouth they do not resemble the wisdom teeth. Their number 
varies. Generally they are few, but sometimes they are many ; in 
one case even the whole number of teeth was seventy-two, viz. eight 
incisors, four canine and twenty-four molar teeth in each jaw.(l) Pos- 
sibly, however, this statement is not perfectly correct, and should be 
considered only as an instance of the coexistence of the deciduous and 
permanent teeth. Sometimes also when the number of teeth is unu- 
sually large, this anomaly is caused by the division of one or more 
into several. 

The second mode in which the number of teeth is increased has 
been termed the third dentition. There is even sometimes a fourth 
dentition, although the instances mentioned of this are hardly credible. 
The principal circumstances of this remarkable phenomenon arc as 
follow : 

a. The third dentition is attended with the same symptoms as those 
of the first and second. The new teeth are smaller than those they 
replace ; they are less permanent and soon decay. 

6. The period of their formation is not determined. If we may 
judge of them from some facts, th«y are formed before they appear : 
probably, however, individuals differ in this respect. 

c. The third dentition usually occurs at a very advanced period of 
life. 

d. The time between the third and second dentition varies. Ge- 
nerally, however, the third teeth appear shortly after the second 
decay. 

fi. In this respect there are differences, some of which depend on 
the quantity, others on the quality. Usually however one or more 
teeth are replaced more frequently than all. The posterior molar 
teeth seem to be those which are renewed most frequently, and even 
if this be not true it is a fact that when they are replaced by others 
the same phenomena are presented as at the second dentition. 

3d. Anomalies in situation and direction. They differ conside- 
rably : 

a. Situation. In this respect the teeth are rarely abnormal, and if 
they are situated in the range they change their place, so that this 
anomaly belongs to the history of the lateral inversion. Thus the 
canine tooth sometimes exists between the two incisors. In other 
cases the canine tooth is replaced by the first anterior molar tooth, and 
exists between it and the second. (2) Sometimes also the teeth are 
developed in parts of the jaws where they are not generally found. 
These abnormal teeth are seen most frequently in the palatine process 



(1) Arnold, Obs. phys. med., p. 69. 

(2) Miel, Observation sur un cas trcsrarc dc transposition des dents ; in the Joum. 
dc med., vol. xl., 1817, p. 83. 



m 



OF THE DIGESTIVE SYSTEM. 245 

of the upper maxillary bone, directly or at some distance behind the 
normal teeth. They are in the lower jaw principally situated in its 
angle. The narrowness of the jaw causes them to project above the 
others, and their direction is also less perpendicular. 

b. Direction. Not unfrequently the teeth are oblique, which de- 
pends particularly on the narrowness of the jaw ; but here their faces 
look to the sides, and their edges are turned backward and forward. 
They are rarely on the contrary reversed, that is, the summits of then- 
roots look to the alveolar edge and the crowns to the opposite region 
of the jaw. 

4th. Anomalies in the form. The form of the teeth is abnormal in 
a great many different modes. 

a. In regard to the whole tooth, this abnormal formation is indicated 
by the adhesion of two adjacent teeth ; this sometimes extends their 
whole distance, and is sometimes confined to a portion of their extent, 
generally to the roots.(l) 

b. Crown. The form of the triturating surface of the crown some- 
times varies very much from the common form. 

The first great molar tooth seems particularly to have a peculiar 
tendency to the imperfect development of this surface ; for we have 
sometimes found it on each side in both jaws with a great number of 
small eminences, a curious analogy with the molar teeth of the hog. 

The rest of the crown, instead of being smooth as usual, some- 
times presents rounded, transverse, and longitudinal elevations and 
depressions, which depend on a deficiency in the secretion of the 
enamel. (2) 

The crown more rarely presents so irregular a form that it appears 
to be compressed from above downward and reversed. (3) 

c. Roots. The roots are abnormal more frequently than the crowns. 
Their principal anomalies are an excess in number and a variation in 
direction. 

Sometimes, although very rarely, the superior molar teeth have 
five roots,(4) and the inferior four.(5) More frequently these latter 
have three. In some subjects we find two in the canine teeth and 
more rarely in the incisors. (6) 

In the abnormal direction of the roots of the teeth they are curved 
very much in the form of a hook, (7) or they are oblique. These two 
anomalies are most frequent, particularly in the great molar teeth, 
which they render more solid. 



(1) Fox, loc. cit., tab. viii., fig - . 8-11. 

(2) Idem, loc. cit., tab. viii., fig. 14. 

(3) Idem, loc. cit., tab. viii., fig. 11, 12. 

(4) Idem, loc. cit., fig. 13. 

(5) Idem, loc. cit., fig. 11. 

(6) Tesmer, Obs, ostcol., vol. i., fig. 1-4, 

(7) Lemairc, loc. cit., p. 254. 

Vol. III. 32 



246 DESCRIPTIVE ANATOMY'. 

5th. Anomalies in size. The upper internal incisors arc principally 
abnormal in this respect from a primitive deviation of formation, being 
much larger than usual. But the size and mass of the teeth may also 
be increased or diminished from too great or too slight activity in the 
formative power. 

The roots particularly increase in size, being affected with hyperos- 
tosis^!) Sometimes, although more rarely, the crown is unusually 
large. We must also mention here the formation of a bony substance 
in the cavity of the tooth, which sometimes adheres to the parietes 
and sometimes is developed in the centre of the soft pulp which fills 
this cavity. (2) 

Atrophia is the opposite of hyperostosis ; when it takes place in the 
crown it sometimes does not extend beyond the enamel, or at least it 
begins with the layer of enamel, although it extends gradually to the 
osseous substance. This latter is unaltered in its texture, and the 
cavity of the tooth is not exposed. The anterior teeth are more sub- 
ject to this disease, which attacks only their anterior face and is seen 
particularly in scrofulous subjects. 

6th. Solutions of continuity. The fractures of the teeth rarely su- 
pervene unless preceded by an alteration of texture, which renders 
these parts brittle. In this case, whether the scale be detached or 
there is simply a fissure, the solution of continuity does not close, while 
it is perfectly healed even when there is a loss of substance, when the 
tooth is perfectly healthy. The latter applies equally to transverse 
and longitudinal fractures. 

The fractures of the roots, however, alone are consolidated. Those 
of the crowns do not heal, which undoubtedly depends on the fact that 
union takes place by an exudation of osseous substance on the outer 
face of the germ of the tooth, in accordance with the law of the normal 
formation of the tooth. It appears then from this, that the external 
membrane, termed the periosteum of the tooth, takes no more part in 
the cicatrization than in the primitive formation of the tooth.(3) 

b. Alterations of texture. 

§ 2128. The alterations in the texture of the teeth are : 
1st. Caries. It is the most common. It usually proceeds from with- 
out inward, more rarely from within outward, begins by the destruction 
of the enamel, and seldom extends beyond the crown. It attacks the 
molar teeth most frequently. It is rarely or never observed at an ad- 
vanced age. 



(1) Fox, loc. cit., tab. i. 

(2) Duval, Cons. mid. sur les dents ; in the Journ. dc mid., vol. xxxvi. ; Bull, de 
lafac. de mid., p. 101. 

(3) Duval, Sur la consolidation des fractures des dents; in the Journ.dc mid., 
vol. xiii., p. 275. 






OF THE DIGESTIVE SYSTEM. 



247 



Sometimes the germ inflames, suppurates, and dies, independent of 
the solid substance of the tooth.(l) Its inflammation seems to precede 
the caries of the tooth. (2) . 

2d. The teeth rarely participate in the general sojtemng ot tne 

3d. The formation in the alveolar processes of cysts filled with 
a liquid sometimes serous and sometimes thicker than serum. These 
cysts partially destroy the root of the tooth. 

The gum frequently softens, and then bleeds at the least touch. 

The abnormal swelling of this tissue with softening constitutes 
epulis, which term embraces, however, very different alterations of 
texture. 

II. CERVICAL AND THORACIC PORTIONS OF THE ALIMENTARY CANAL. 

§ 2129. The cervical and thoracic portion of the alimentary ca- 
nal^) are much more simple than the cephalic. They include the 
pharynx and the esophagus. The first begins at the posterior extre- 
mity of the cavities of the mouth and nose, and is uninterruptedly 
continuous with the esophagus, which is connected with the stomach. 



A. PERFECT STATE. 



I. PHARYNX. 

§ 2130. The pharynx(A) extends in a straight line from the base of 
the skull and the fauces to the lower extremity of the larynx, or to the 
fifth cervical vertebra. Its mean measure is four inches long, and one in 
diameter at its broadest part when moderately distended. Below this 
point it contracts, then dilates again, becomes narrower, and is finally 
continuous with the esophagus. 

Its posterior straight face is situated directly before the five superior 
cervical vertebrae and the anterior muscles of the neck, behind the ca- 
v\ty of the mouth and the larynx, between the great vascular and 
nervous trunks of the neck. 

Its upper extremity or arch {fornix) is united by some cellular tissue 
to the lower face of the body of the basilar bone and the petrous por- 
tion of the temporal bone. Some muscles to be described hereafter 

(1) Duval, loc. cii., vol. xxxvi., p. 99, 100. 

(2) Serrcg, loc. cit., p. 51. ..-,«. , c ,o t Po n #nni 

(3) Fabricius of Aquapendente, De gula el ventnculo, Padua, 161B.— J. *antom, 
De gula et vcntriculo, Turin, 1742. 

(4) Santorini, De pha^ynge ; in the Obs. anat, cap. vn. 



248 DESCRIPTIVE ANATOMY. 

attach it to different parts of the head. Upward and backward are 
the posterior nostrils, forward the orifice of the cavity of the mouth, 
backward and on the sides those of the Eustachian tubes. These 
different openings exist at its upper part, which is divided by the soft 
palate to a certain extent into an anterior and a posterior passage. 

§ 2131. It is surrounded externally by a thin layer of cellular tis- 
sue, which attaches it loosely to the adjacent parts. Below this layer 
is another, which is easily separated from it ; this is also cellular and 
is filled with fat, and intimately unites it with the subjacent muscular 
layer. The nervous and vascular trunks which enter into the proper 
membranes of the pharynx are distributed in them. 

§ 2132. The muscular tunic of the pharynx is formed principally 
by the three constrictor muscles (JVE. conslrictores pharyngis)~(\) a 
superior, a middle, and an inferior. These muscles have several com- 
mon characters, which are : 

1st. They surround the pharynx backward and on the sides ; their 
lateral extremities are attached to the adjacent hard parts before the 
pharynx, especially to several bones of the face and skull, to the hyoid 
bone and to the larynx. 

2d. They are composed of fibres which proceed from below upward 
and from without inward, and which extend by radiation from each 
side to the median line. 

3d. They partially cover each other from below upward. 

4th. They are voluntary muscles. 



A. CONSTRICTOR PHARYNGIS INFERIOR. 

§ 2133. The constrictor pharyngis inferior or the crico-thyreo- 
pharyngeus muscle arises by from two to four triangular digitations, 
from the cricoid and the thyroid cartilages. 

The lowest and smallest is attached below the crico-thyroideus 
muscle to the lower part of the side, and to the lower part of the pos- 
terior horn of the cricoid cartilage. 

The upper, the larger, is sometimes single and sometimes triple ; it 
arises from all the posterior part of the side of the thyroid cartilage, 
excepting the lower region occupied by the crico-thyroideus muscle, 
which is situated between it and the lower digitation. 

The fibres of this muscle proceed from all these points, divided into 
several fasciculi in a greater or less extent, and go toward the median 
line, so that the inferior are almost transverse, while the others ascend 
more the higher they become, and unite at angles more and more 
acute with those of the opposite side on the median line. 

(1) Santorini, Septemdecim tabula; tab. vi. 



OP THE DIGESTIVE SYSTEM. 249 

The upper head of this muscle is only about an inch below the 
upper extremity of the pharynx. 



B. CONSTRICTOR PHARYNGIS MEDIUS. 

§ 2134. The constrictor pharyngis medius muscle (M. constrictor 
medius pharyngis, s. glosso-hyo-pharyngeus, s. kerato-chondropharyn- 
geus, s. cephalo-pharyngeus) is much smaller and weaker than the 
preceding. It arises from the hyoid bone and the tongue, generally 
by two heads. The inferior or posterior, the smaller, termed the hyo- 
pharyngeus muscle, comes from the posterior part of the upper edge of 
the great horn of the hyoid bone. 

The upper or anterior, which is the larger and is termed the glosso- 
chondro-pharyngeus muscle, arises from the small horn of the hyoid 
bone and from the base of the tongue. 

Its lower fibres are transverse and even convex downward ; the 
upper are very oblique and are generally pointed, and either alone or 
blended with the upper fibres of the constrictor pharyngis inferior mus- 
cle, extends as the cephalo-pharyngeus muscle ; to the basilar process 
of the basilar bone, and is attached to its lower face by fleshy or tendi- 
nous extremities. 

C. CONSTRICTOR PHARYNGIS SUPERIOR. 

§ 2135. The constrictor pharyngis superior or the glosso-mylo- 
pterygo-pharyngeus muscle arises from the posterior part and the side 
of the root of the tongue, from the inner face of the lower maxillary 
bone, near the posterior molar tooth, from the hook of the pterygoid 
process, and from the tendon of the peristaphylinus externus muscle, 
often also a little from the petrous portion of the temporal bone and 
from the styloid process, and blends with the posterior part of the 
genio-glossus and buccinator muscles, and often also with the lower 
portion of the stylo-pharyngeus muscle. 

Its lower fibres are transverse ; the upper describe an arch which is 
convex upward. 

D. STYLO-PHARYNGEUS. 

§ 2136. The stylo-pharyngeus muscle (JVf. stylo-pharyngeus, s. le- 
vator, s. dilator pharyngis) is large, elongated, and rounded. It arises 
by a broad and short tendon from the inner face and the lower edge of 
the styloid process of the temporal bone. Thence it goes inward and 
downward. It is at first separated from the constrictor pharyngis su- 
perior muscle by a greater or less quantity of fat ; it goes from above 
downward and from without inward, passes under the lateral part of 



250 DESCRIPTIVE ANATOMY. 

the constrictor medius muscle, and is distributed on the lateral and 
posterior wall of the constrictor medius, and adheres to its vascular 
tunic very intimately by a dense cellular tissue. 

Its upper fibres curve in an arch from below upward and interlace 
with those of the superior constrictor. The inferior separate like a 
pair of forceps. Both descend to the base of the upper horn of the 
thyroid cartilage, and are attached to its posterior edge. 

This muscle raises the pharynx and the larynx, and dilates the first 
of these two cavities transversely. 

§ 2137. The vascular tunic of the pharynx which is considerably 
thick comes next to the muscular portion. 

The inner tunic or the mucous membrane is very thin, smooth, and 
reddish white. It is uninterruptedly continuous above with that of the 
mouth and nose, below with that of the esophagus. 

II. ESOPHAGUS. 

§ 2138. The esophagus{\) is that part of the alimentary canal in- 
cluded between the pharynx and the stomach. It is narrower than 
either, and is continuous with them at its two extremities by tunnel- 
like portions. 

This canal is situated in the posterior mediastinum, and extends its 
whole length before the vertebral column. Its upper part corresponds 
directly to the anterior face of the spine from the fifth cervical vertebra 
and the cricoid cartilage, where it commences, to the fifth dorsal ver- 
tebra, although it frequently also inclines a little to the left. From this 
point to the ninth dorsal vertebra it inclines slightly to the right ; it 
then returns on the anterior face of the column, passes through the 
esophageal fissure of the diaphragm, and soon terminates at the upper 
or left orifice of the stomach. 

At its upper part it is situated behind the trachea. From the fifth 
dorsal vertebra it is found between the aorta on the left and the azygos 
vein on the right side. It is united to the adjacent parts by a very 
loose cellular tissue. 

§ 2139. The esophagus is the narrowest part of the alimentary 
canal. Even in its greatest dilatation its diameter is not an inch. It 
is equally broad in every part, except at most the slightly contracted 
portion which passes through the diaphragm. 

The muscular tunic is considerably thick ; it is generally at least 
a line in thickness. 

It is composed of two layers, one external longitudinal, the other 
internal transverse, the first of which is twice as thick as the second. 
The longitudinal fibres usually commence above by three fasciculi or 

(I) J Bleuland Obscrrationes anatomico-mcdicm de sana et morbosa oesophagi 
structu'ra, Leyden, 1785.— V. Malacarne, SuW esofago, sullc intestine, e sopra alcunc 
valvulo del tubo alimentare, Padua, 1803. 

\ 



OP'THE DIGESTIVE SYSTEM. 251 

heads, a middle and two lateral. The middle head arises by a tendon 
from the centre of the posterior face of the cricoid cartilage directly 
below its upper edge, and expands a little in descending. The two 
lateral heads, which are fleshy, descend from the lower edge of the 
constrictor pharyngis inferior muscle. These three fasciculi unite 
some inches below the upper extremity to form a muscular membrane 
which is uniformly extended. 

The circular fibres are a continuation of the inner posterior part of 
the constrictor pharyngis inferior muscle, but are much thinner than 
those of this muscle. 

The upper are transverse ; the next are oblique from above down- 
ward and from without inward, intercross with those of the opposite 
side, and describe spiral lines ; the inferior, like the superior, form 
straight rings. This canal for about an inch at the upper end of the 
esophagus presents no circular fibres on its anterior face, and as the 
longitudinal fasciculi are not united in this place, the esophagus is 
here much less muscular and more extensible than in other parts. 

The cellular or vascular tunic comes next to the muscular, and is 
attached to it very loosely, while it adheres strongly to the internal 
membrane with which it forms an internal canal which is easily de- 
tached from the muscular membrane. 

In this tunic there are numerous muciparous glands arranged very 
compactly and composed of smaller granulations, which diminish in 
number and size as they approach the lower extremity. 

The inner or villous tunic is whitish, solid, and presents, on its inner 
face, numerous and very narrow longitudinal grooves separated by 
parietes. We ought not to consider it as the same with the pre- 
ceding^ 1) 

Its inner face is covered with a thinner, more delicate, and moist mem- 
brane, which is evidently an epidermis, and which suddenly terminates 
at the lower part of the esophagus at the part where it is continuous 
with the stomach. The folds of this epidermis are easily separated by 
boiling and maceration, although it is difficult to detach it entire unless 
it is morbidly thicker and firmer from some pathological change. 
Farther the lower extremity of the esophagus is detached from above 
downward in one or more parts sometime after death, which undoubt- 
edly arises from the fact that the fluid secreted by the glands of the 
esophagus and cardiac portion of the stomach soften and dissolve it 
and also the loose cellular tissue which unites it to the cellular tunic. 



(1) Soemmerring (Eingeweidelehre, p. 216) describes these two tunics as forming 
but one, termed the vascular or internal glandular tunic ; he say3 that the inner 
membrane and the vascular membrane of the stomach are continuous with it. It is 
true that the internal membrane of the stomach is continuous with that of the 
esophagus, and its vascular membrane witli that of this canal. Other anatomists 
err still more in considering the villous tunic of the stomach and intestinal canal as 
a continuation of the epidermis of the esophagus. 



252 DESCRIPTIVE ANATOMY. 

§ 2140. After the food is masticated by the teeth in the cavity of 
the mouth, mixed with the saliva and formed into a soft mass, the 
muscles of the tongue, the hyoid bone, the pharynx, and the esophagus 
propel it successively toward the stomach ; this constitutes deglutition 
(deglutitio).(l) In order to this, the mass of food is moved from before 
backward in the cavity of the mouth, which motion requires the close 
of this cavity by approximating the jaws and lips! At the same time, 
the tongue is moved by its muscles, so that its edges are raised and its 
centre is depressed, and it thus forms a kind of groove, which touching 
the palate makes a canal, in which the food proceeds from before back- 
ward, because there is the least resistance in this direction. When it 
has passed through this course, the genio-glossi and genio-hyoidei 
muscles, which restore the tongue to its position and carry it forward 
also favor its progress, because they thus raise the soft palate, to which 
motion also the levator muscles of this latter contribute. When the 
food has arrived at this place the constrictor muscles of the pharynx 
contract ; at the same time the depressors of the soft palate and the 
stylo-glossi muscles act to raise the tongue and contract the isthmus 
of the fauces ; the contractions of the constrictor pharyngis superior 
muscle press the pharynx against the soft palate, and thus close the 
nasal fossa? as they had been before by raising the soft palate. The 
stylo-pharyngei muscles, then the constrictors of the isthmus of the 
fauces, raise and dilate the pharynx, so that the food can enter, there 
more easily. 

The genio-hyoidei, the mylo-hyoidei, the thyro-hyoidei and the hyo- 
glossi muscles carry the larynx forward and upward ; this motion 
favors the closing of the glottis by the epiglottis, which the pressure of 
the food also serves to depress, so that nothing can enter the air pas- 
sages. 

All these parts being extremely irritable act very rapidly and easily. 
Deglutition, which is at first voluntary, becomes involuntary in the eso- 
phagus, although this passage receives its nerves from the pneumo- 
gastric nerves. 

B. ABNORMAL STATE. 
I. DEVIATIONS OF FORMATION. 

§ 2141. 1st. Primitive deviations. Sometimes but rarely the pha- 
rynx and the esophagus terminate in a cul-de-sac, one at its lower the 
other at its upper part, from a primitive deviation of formation. In the 

(1) Schulze, De deglutitionis mcchanismo, Halle, 1739.— F. B. Albinus, De dcfflu- 
titione, Leyden, 1740.— VVcntz, De deglutitionis mechanismo, Erlangen, 1780 — P J 
Sandifort, Deglutitionis mechanismus, verticali sectionc narium, oris,fa.ucium iliiLs- 
tratus, Leyden, 1805. 



OP THE DIGESTIVE SYSTEM- 253 

first place the cavity of the mouth also is generally at least imper- 
fectly developed, and the lower jaw is wholly or in great part deficient. 
The same thing occurs when the pharynx opens in the neck by a very 
narrow orifice. 

Another primitive deviation of formation which is more rare, is the 
division of a part of the esophagus into two passages situated at the 
side of each other.(l) 

We cannot always determine if the contractions of the esophagus, 
which depend on the abnormal folding of the inner membrane without 
any morbid change, are primitive deviations of formation, or are pro- 
duced consecutively by a simple increase of this membrane. 

We must however admit that this latter sometimes occurs, since 
accidents frequently appear only a little while before death, 

2d. Accidental deviations of formation. Dilatations of the esopha- 
gus are generally accidental. They usually occur after contractions 
situated below them, and in this case they are general. 

More unfrequently a portion of the circumference of the canal 
appears dilated in a cul-de-sac. (2) In one case the pouch was cer- 
tainly caused by a hernia of the internal membrane through the 
muscular tunic,(3) while in another this latter also contributed to 
it.(4) 

Pouches of this kind occur only at the lower extremity of the pharynx 
or at the commencement of the esophagus, doubtless on account of the 
sudden contraction of the alimentary canal in this place, and because 
the esophagus is less muscular there than in other parts. 

Ruptures of the esophagus which are sometimes transverse(5) and 
sometimes longitudinal, (6) are only a greater degree of the hernia 
of the inner membrane. They are sometimes caused by abnormal 
brittleness. 

When the contractions are permanent, they generally supervene 
after a morbid alteration of texture, as thickening and induration of the 
coats of the esophagus, so that they are rarely pule deviations of forma- 
tion. Sometimes, however, they depend originally on a simple abnor- 
mal contraction of the muscular fibres, which continues even after 
death ; and the greater hardness in this part does not result from an 
alteration of texture, but only from a stronger contraction of the mus- 
cular tunic, although the continual pressure of the latter on the inner 
membrane may also change its texture, and excite in it inflammation, 



(1) Blaes, Obs. medicm rariorcs, tab. vi., fig. 2. 

(2) Meckel, Handbuch der pathologischen Anatomic, vol. ii. — Bell, Surgical obser- 
vations, pt. i., London, 1817, p. 167, tab. ii. 

(3) Bell, loc. cit. 

(4) Ludlow, Med. obs. and inq., vol. iii. 

(5) Boerhaave, His. morbi atrocis, Leyden, 1724. 

(6) Monro, Morbid anatomy, p. 311. 

Vol. III. 33 



254 DESCRIPTIVE ANATOMY. 

followed by effusion and suppuration, which render the induration 

permanent.(l) 

II. ALTERATIONS OF TEXTURE. 

§ 2142. The most common alteration in the texture of the esopha- 
gus, is an abnormal hardness, usually attended with thickening, and 
consequently with a greater or less contraction, or even with a total 
closing of it, (2) which state is termed a scirrhus, and in which the dif- 
ferent tunics of the passage are more or less blended in a mass, some- 
times homogeneous and cartilaginous, sometimes divided into several 
compartments by tendinous septa. ' Commonly then the texture of the 
inner face is altered. This alteration is not observed in all parts indis- 
criminately; it is more frequent at the upper and lower extremities of 
the esophagus, in the former place, on account of the sudden contrac- 
tion of the pharynx ; in the latter, because the lower portion of the eso- 
phagus tends to contract, since the two orifices of the stomach are per- 
fectly closed during digestion, so that it is very easily injured by sub- 
stances passing through it. 

Abnormal communications between the esophagus and the adjacent 
parts, particularly the trachea,(3) the lungs,(4) the aorta,(5) may oc- 
cur from cancer or common ulcerations. This state may also be oc- 
casioned by ulcers formed primitively in the aorta. (6) 

We can sometimes, but not always, determine from the state of the 
parts, which was the primitive disease. 

Beside the alterations of texture in the membranes mentioned, ex- 
crescences, funguses, and polypi of different kinds, are sometimes, al- 
though rarely, developed in the pharynx and the esophagus ; these 
arise from the inner face of this canal, (7) and usually have their roots 
in the mucous and vascular membranes. They are sometimes so long, 
that commencing near the upper extremity of the esophagus, they de- 
scend to the stomach*. They are sometimes formed by fibres perpen- 
dicular to their base, (8) are sometimes lobed(9) and suppurate. (10) 

Real ossifications are still more rare.(ll) 

(1) Baillie relates several instances of it : we also have seen it, and like Baillie in 
the cadavers of females. Mauchart, De struma ccsophagi ejusque coalitu, Tubingen 
1742. 6 ' 

(2) Gyser, De callosa ccsophagi anguslia, Strasburpr, 1770.— J. Bleuland, Dc dif- 
Jiciliaut impeditu alimentorum depulsione, Leyden, 1780. 

(3) Van Doeveren, Obs. anat.pathol. Leyden, 1789, obs. ii. 

(4) Bleuland, loc. cit., obs. i. p. 48. fig. 112. 

(5) Van Doeveren, loc. cit., obs. i. 

(6) We have one very remarkable case before us. 

(7) Monro, loc. cit., p. 184-189.— Baillie. 

(8) Baillie, loc. cit. 

(9) Monro, loc. cit., p. 188. 
(10} Baillie, loc. cit. 

(11) Meckel, Handbuch.dcr pathologisch.cn Anatomic, vol. ii. p. 2. p. 227. 



OF THE DIGESTIVE SYSTEM, 255 

ARTICLE SECOND. 

MIDDLE AND INFERIOR PORTION OF THE ALIMENTARY CANAL. 

§ 2143. The middle region of the digestive system comprehends 
the stomach and the small intestine, and the most important glandular 
organs of this system, the liver, the spleen, and the pancreas. This is 
the largest and the most important portion, because digestion takes 
place in it, for 'which the preceding portion only prepares, while the 
terminating portion serves for the expulsion of the residue. 

The stomach, the liver, the spleen, and the pancreas, with the com- 
mencement of the small intestine, the duodenum, into which the pan- 
creas, the liver, and the stomach open, occupy the upper part of the 
abdominal cavity. They are separated from the lower, which is larger, 
by a large transverse fold of the peritoneum, the transverse meso-colon. 
It is not, however, necessary to describe the lower portion of the intes- 
tine after these glands, nor to separate the large intestine from the 
small, since they are both situated in the same cavity, their texture is 
essentially the same, and they are uninterruptedly continuous with 
each other. 

It is customary to describe the peritoneum before mentioning the 
parts of the digestive system it envelops ; but as these are not the only 
parts covered by it, the prolongations whioh extend from its outer sac 
to the organs covered by it, cannot be clearly described until the situa- 
tion and form of these organs are well known : finally, the important 
anomalies of this membrane, especially those which occur in hernias, 
being dependent on those, to which several of the parts it envelops are 
subject, it is better to defer the description of the peritoneum until we 
mention the different systems it supports. This is the method followed 
by Roux in the Anaiomie descriptive of Bichat. 

We shall not describe on this occasion the cavity of the abdomen, 
the most general characters of which have been already mentioned. 

A. PERFECT STATE. 

§ 2144. The different regions of the middle portion of the alimentary 
canal, doubtless differ very much in respect to their capacity; but they 
are very analogous in regard to texture, in which, however, they differ 
on the contrary, from the upper and lower portions. The longitudinal 
fibres of the muscular tunic completely surround this portion of the 
canal ; the vessels which go to it are more numerous, and anastomose 
together more frequently, and finally, the inner surface of the mem- 
brane is more or less uneven, from prominences which do not exist in 
the other two portions. 



256 DESCRIPTIVE ANATOMY. 



I. STOMACH. 



S 2145 The stomach (ventriculus, stomachus),(\) the broadest part 
of the alimentary canal, is included between the esophagus and the 
duodenum. The portion of this canal in the cavity of the abdomen 
commences with it. The alimentary substances all fall directly within 
it, assimilation there commences, and they are there changed into a 
liquid of a peculiar character called chyme (chymus). 



A. SITUATION. 



§ 21-46. The stomach is situated at the upper part of the abdominal 
cavity, under the left false ribs. Sometime*, when it is much larger, 
it descends into the umbilical region. Its direction is oblique from above 
downward and from left to right. Its upper extremity touches the 
diaphragm ; the lower extends to near the lower edge of the left or 
square lobe of the liver. . 

§ 2147. The spleen is situated near its left extremity ; behind its 
posterior face is the pancreas, below it the transverse colon, above it 
the left or square lobe of the liver and the lobe of Spigel, which is em- 
braced by its upper curve. 



B- FORM. 



§ 2148. The stomach has the form of an elongated cone, a little 
curved on itself, and is somewhat similar to a bagpipe. Its right ex- 
tremity is the narrowest, arid its left the broadest portion. 

We distinguish in it two orifices, two curves, and two culs-de-sac 

The upper or left orifice, termed also the cardiac (ostium ventriculi 
sinislrum, s. superius, s. cardia), occupies the highest part of the 
stomach near its left cul-de-sac. It serves as the limit between this 
viscus and the esophagus, which, however, are continuous with each 
other and separated by no prominence, so that the lower extremity of 
the esophagus gradually enlarges. 

The inferior or right orifice, termed also the pylorus (ostium ventri- 
culi dextrum, s. inferius, s. pylorus, s. janitor,)(2) is the limit between 
the stomach and the duodenum. Here the transition is not gradual 
and imperceptible as on the left side, but occurs by a prominence termed 
the valve of the pylorus (valvula pylori). 

The faces and the curves of the stomach are included between these 
two orifices. 

(1) Beside the works of Fabricius, of Aquapendente, Gfisson, and Fantoni, already 
cited, consult also J. D. Metzger, Ventricutus hum anus anatomice et physiologice 
consideratus, Konigsberg, 1788. 

(2) Leveling, Pylorus anatomice atque physiologice consideratus, Strasburg, 1764. 



OF THE DIGESTIVE SYSTEM. 257 

The posterior and the anterior faces, when the stomach is more 
or less distended, are uniformly convex, but when the stomach is 
empty they are straight, flat, and in contact. 

The upper or small curve, the diaphragmatic edge, is situated be- 
tween the right side of the upper, and the left side of the lower orifice; 
it is concave and much smaller than the lower, which is also called 
the great curve, the colic edge. 

When the stomach is empty, the two curves appear as more or less 
distinct edges, which establish a well marked separation between the 
two faces. But when the viscus is full, they are very rounded, and 
insensibly continuous with the two faces. • 

The base, tubercle, or great cul-de-sac of the stomach, the splenic ex- 
tremity {fundus, s. saccus ccecus), is a prolongation in the form of a cul- 
de-sac which extends from right to left on leaving the left side of the 
upper orifice, and which proceeds about three inches beyond the inser- 
tion of the esophagus. 

This portion of the stomach is not much narrower than its centre. 
On leaving it and the cardiac orifice, the viscus slightly enlarges to a 
little beyond its centre from left to right.. From this latter point to the 
pylorus, it gradually contracts very much.. 

When one or two inches from the pylorus, the great curve suddenly 
inclines inward, but immediately resumes its former direction, although 
it does not afterward describe so great a curve as in the rest of its 
course. Hence, there is a fissure, opposite which the right portion of 
the small curve, instead of preserving the concave form which it pos- 
sessed from the cardiac orifice, becomes convex outward, although in 
this place there is no contraction, between which and the pylorus is a 
dilatation. 

The portion of the stomach farthest from the right side, is termed the 
antrum of the pylorus, or the small cid-de-sac [antrum pylori). 

C. DIMENSIONS. 

§ 2149. The size of the stomach varies much in the same indivi- 
duals, in the state of health at different periods ; as this viscus dilates 
considerably when filled with food, and contracts when empty. Its 
capacity is diminished particularly in the transverse direction, and 
often to such an extent that the stomach is smaller than the large in- 
testine is when in its usual and moderate state of distention. 

Generally, when the stomach is not unusually full, it is one foot 
long from the base to the pylorus, three or four inches high in it high- 
est part, and about as many broad from before backward. Its surface 
is about one square foot in extent. 

». ATTACHMENTS. 

§ 2150. The stomach is attached on each side at its upper orifice 
by a short fold of peritoneum, termed the phreno- gastric ligament (L. 



258 DESCRIPTIVE ANATOMY. 

phrenico-gaslricum), which extends on the left to the commencement 
of the base, and descends on the right along most of the small curve. 
This ligament is attached forward and upward to the superior lumbar 
portion of the diaphragm. 

To this ligament is attached another which is much longer, the 
gastro-splenic ligament (L. gastro-splenicum), which extends from the 
base of the stomach to the fissure of the spleen, where it is attached, 
and which is continuous below with the great epiploon. 

The stomach is united to the transverse colon by the great epiploon, 
and to the liver by the small epiploon, internal prolongations of the 
peritoneum, which we shall describe after giving the history of this 
membrane. 



E. MEMBRANES. 

§ 2151. The stoniach is enveloped by the peritoneum in every part, 
excepting a narrow ring which exists along the great and small curve, 
and along which the blood-vessels proceed. 

Below this peritoneal coat, directly on its inner face, is the muscular 
membrane,(l) which is very strong, but stronger than in the great and 
the small intestine, although weaker than in the pharynx and rectum. 
It is about half a line thick, and its texture is more complex than in the 
rest of the alimentary canal, and we may, at least in some parts, de- 
monstrate three layers. 

The external layer is formed of longitudinal fibres, which mostly 
blend with those of the esophagus and duodenum, and are uninter- 
ruptedly continuous with them. These fibres are very much developed 
at the upper part of the stomach, around its small curve ; they how- 
ever cover all its surface. 

The middle layer is formed by annular fibres, representing rings, the 
centre of which correspond to the longitudinal axis of- the stomach. 
They commence at the base of the stomach, and interlace with each 
other, proceed a little obliquely, and cover the whole stomach to the 
pylorus, where they are strongest. 

They are termed transverse or oblique fibres. They form the thick- 
est layer. 

Below this layer there is a third, (2) which is very evident on the 
left side, and on the small curve, and which also surrounds the stomach 
circularly, but in an opposite direction from the preceding, that is, lon- 
gitudinally. They are the continuation of the circular fibres of the 
esophagus, and frequently interlace with the oblique fibres. 

The vascular membrane of the stomach is thicker, more vascular, 
and more distinct from the internal membrane than in the esophagus. 

(1) D. G. Galeati, De cornea ventriculi et intestinorum tunica ; in Comm. Bonon. 
1745. — Bertin, Description des plans musuleux dont la tunique charnuede Vcslomac 
humain est composie, vol. ii. p. 235. 

(2) Galeati (loc. cit., p.240) described this membrane long before Bertin. 



OP THE DIGESTIVE SYSTEM. 259 

It is uninterruptedly continuous with the vascular tunic of this canal, 
but not with the inner or villous membrane. 

The villous membrane of the stomach is thin, soft, loose, and spungy, 
softer and looser, but a little thicker than the corresponding membrane 
of the esophagus. It usually assumes, soon after death, a yellowish, 
brownish, or reddish tint.(l) Not unfrequently, especially when 
examined shortly after death, it presents in a greater or less extent, 
especially at the base and at the small curve, a very red color, caused 
by a network of small vessels almost exclusively veins. We generally 
consider this state as the consequence of an inflammation which had 
affected the organ daring life ; and conclude from its existence that the 
patient had been poisoned. But attentive examination demonstrates 
that it supervenes during the struggles of death, without any sus- 
picions of such a cause, and is occasioned particularly by the sudden 
suspension of the circulation in the lungs. (2) 

When' the stomach is not distended, its villous membrane, and con- 
sequently its inner face, present numerous large and small-wrinkles, 
which are arranged very irregularly. But these wrinkles disappear 
when this viscus is even very moderately distended, so that when we 
look at the membrane with the naked eye its inner face seems smooth, 
although when examined with a microscope this same face seems 
divided^ by several small intermediate parietes ; which enlarge to- 
ward the pylorus and by this are still more similar to the villosities of 
the intestines, into numerous compartments ; these are arranged very 
compactly, like the cells in a bee-hive.(3) The cellules are larger 
but fewer in the left half of the stomach, and are separated by simple 
septa. In the region of the pylorus, these septa present numerous 
grooves which render them still more similar to the villosities of the 
intestines, although they are much smaller in other respects than these 
latter.(4) 

Beside numerous slight depressions, which are the orifices of small 
simple glands, the inner membrane of the stomach also presents, espe- 

(1) The French physicians having studied for several years the alterations in the 
mucous membrane of the digestive canal, they have naturally considered also its 
normal conditions. Rousseau (Des diffirens aspects que ■prisente, dans Vetat sain, la 
membrane muqueuse gastro-intcstinale ; in the Archiv. gener. de mid., vol. vi. p. 
321) has observed, that in the healthy state it is white or slightly rosy white. This 
primitive color varies in different parts of the alimentary canal. Thus, the mucoua 
membrane of the pharynx is slightly rosy; that of the esophagus is white, particu- 
larly at its lower part ; in the stomach it has a slight rosy tint as in the pharynx. 
This rosy color becomes less intense in its pyloric portion, changes to white in the 
duodenum preserves this appearance in the rest of the small intestine, then becomes 
of a pale white in the ccecum, the colon, the commencement of the rectum, and re- 
sumes its slightly reddish color near the end of this last intestine. _ P. T. 

(2) J Yelioly, On the vascular appearance of the human stomach, which is fre- 
quently mistaken for inflammation of that organ ; in the Med. chir. trans., vol. iv. 
1813, p. 371-424. 

(3) Hcwson, Expcrim. inq., vol. ii., p. 173. 

(4) E. Home has figured this {Observations on the gastric glands of the human 
stomach and (he contraction which takes place in that viscus ; in the Phil, trans., 
1817, pt. i., p. 347, pi. i, xviii, xix. 



260 DESCRIPTIVE ANATOMY. 

cially near, the two orifices, others which are larger and which lead to 
more or less apparent large glands. These last glands form at the 
union of the esophagus and stomach a very marked prominence from 
three to four lines broad, which separates the two cavities to a certain 
extent. 

The villous membrane of the stomach is uninterruptedly continuous 
with that of the esophagus and intestinal canal. But it does not seem 
to be connected with the epidermis of the esophagus, since we may 
without the least violence separate this epidermis from it and from the 
villous tunic of the esophagus around the cardiac orifice. 

The membranes of the stomach vary in thickness in different indi- 
viduals, and in different parts of this viscus of the same individual, and 
at different periods.(l) 

Generally, in the first respect, they are thickest in those male 
subjects who enjoy good health, and in the second they are thicker, as 
is easily imagined, the less the stomach is distended. In regard to the 
third we may admit that the peritoneal coat is equally thick in every 
part, while the others are much thinner in this cul-de-sac of the 
stomach than in the other parts of the viscus, and are thickest near 
the pylorus, where they are frequently six times thicker than at the 
base. 

F. VALVE OF THE PYLORUS. 

§ 2152. The valve of the pylorus (valvula pylori) is formed by 
the circular fibres of the muscular tunic, and also by the vascular and 
mucous tunics of the stomach and duodenum. The. first two mem- 
branes are much thicker in this place, and all three are reflected on 
themselves from without inward. 

The longitudinal fibres in the peritoneal coat only pass on this point 
to the outside. 

It is very easy to remove the valve by cutting or raising the longi- 
tudinal fibres. But there is always a contraction at the union of the 
stomach with the duodenum. 

A peculiar glandular substance has been mentioned as situated be- 
tween the muscular and peritoneal tunics, and as forming the pylorus 
and determining its form ;(2) but with the utmost care in our dissec- 
tions we have nev.er been able to discover the least trace of this sub- 
stance, although we always find a very thick glandular layer before 
the pylorus, below the muscular membrane of the duodenum. 

The form of the Valve varies. 

It generally circumscribes the whole orifice of the viscus, and it is 
sometimes circular and sometimes more or less oval ; in the latter case 
its longitudinal diameter usually extends from above downward. 

(1) Yelloly, loc. cit., p. 400, 402* 

(2) Scemmcrring-, Eingeweidelchrc, p. 236.— Portal, An. med. vol. v., p. 161. 



OF THE DIGESTIVE SYSTEM. 



261 



It is more unfrequently semicircular, surrounding only a part of the 

Between this formation and the preceding there is an intermediate 
degree in which the valve differs considerably in its breadth, according 
to the different parts in which it is examined. 

It is sometimes larger and sometimes smaller. 

It is not certain that we ought always to admit that it possesses 
during life the form which it has after death. 

We cannot determine precisely what effect a given form of the valve 
has even, admitting its existence and permanence during life, on the 
action of the valve and on the more or less closing of the pylorus by 
it since it is evident that the degree of contractility m the circular 
fibres which contribute principally to form this fold has still more 
influence. 

O. TRANSIENT MODIFICATIONS IN THE FORM AND SITUATION OF THE STOMACH. 

& 2153. The stomach presents regularly transient modifications in 
its situation, according as it does or does not contain food, lhese 
modifications correspond then to the different states of digestion. 

The stomach is not only smaller when perfectly empty than when 
it contains food, but then its form is not cylindrical. Its anterior and 
posterior faces touch and its two edges are distinct from each' other, 
while when full, its edges and faces are imperceptibly continuous. > 

A still more remarkable modification occurring during digestion, is, 
that the stomach is then divided into a right and a left half ; this occurs 
about its centre, and is more or less distinct. The left half contains 
the fluids and the right the solid substances, and the former pass out 
from them into the small intestine without proceeding necessarily or 
at least entirely through the right half and the pylorus. (1) 

The orifices of the stomach are more or less perfectly closed during 
digestion; when, however, this process has continued some time the 
pylorus opens, and the mass contained in the stomach passes through 
it to descend into the duodenum, in proportion as it is digested. 

The situation of the stomach also changes during digestion; it turns 
on its axis, so that its anterior face looks more upward and the poste- 
rior downward, although this apparent change in situation depends 
principally on that in its form above mentioned. 

H. FUNCTION OF THE STOMACH. 

§ 2154 The inner membrane of the stomach secretes the gastric 
juice (succus gastricus), a fluid the exact nature of which it is .difficult 
to determine, as it is always more or less mixed with the substances 

(1) E Home, Lectures on comparative anatomy, vol. i., p- 138. 
Vol. III. 34 



262 DESCRIPTIVE ANATOMY. 

introduced into this viscus. It generally contains an uncombined 
acid.(l) 

It however appears to be sometimes acid and sometimes neutral in 
the same subject. Its base seems to be an albuminous substance very 
analogous to that in the saliva. (2) Perhaps its composition is not 
always the same, and varies from the nature of the substances which 
act on the inner membrane of the stomach. The action of this fluid, 
united perhaps with that of the bile, changes the food into a mucila- 
ginous, gray, and thick pulp, of a disagreeable odor and taste, termed 
chyme (chymus). The nature of this pulp varies with that of the ali- 
mentary substances ; it includes more solid parts and less of salts than 
any other of the animal fluids. It contains much carbon and albumen, 
but no gelatine, at least if we may judge from some experiments. It 
forms gradually in the pyloric portion. (3) 

The formation of chyme, or the digestion in the stomach, is singu- 
larly favored by the closing of its two orifices. We must also mention 
among the causes which favor this process the motions of the sto- 
mach, which are at first vague and irregular, but which gradually 
take place about the end of chymification from the cardiac to the 
pyloric orifice. 

I. SEXUAL DIFFERENCES. 

§ 2155. The stomach is the only portion of the alimentary canal 
which presents sexual differences. It is larger, shorter, and broader 
in the male ; smaller, narrower, and longer in the female. Its mus- 
cular coat, like that in the whole alimentary canal, is generally also 
thinner in the female.* 



IX. SMALL INTESTINE. 

§ 2156. The small intestine (intestinum tenue,)(4) the narrowest and 
thinnest portion of the intestinal canal, is included between the sto- 

(1) This opinion has at least become very g-eneral since thp t,W aF <3™n 
although the experiments of Montegre tend to prove hat i U w „£ P allanzani > 
Prout asserts that the free or at leU thr. nZFi * \ • , r ot alwa V s correct, 
stomach of animals is the hydrochlor c and Uhaf thoUt " ?*?*»* in the 

viscus are the alkaline hyd/ochlorateT^S .*S££ '& S pT^lt™'? "* 
rived at the same result bv analwino- +h k,,;a './,,' p ' >' ° nlld ren has ar- 

attack of dyspepsi.. (Ann^^MofoXm, JuTyT * * ™« dU ^ **$»* 

2 Bostock, m the Med. chir. trans!, vol. i v., p. 1 77 F " T ' 

(3) Marcet, in the Med. chir trans vol vi n K97 r> i tuta ■ 

tose et le sang en gtn&ral ; in the Jovrr, ,~, P \ G27 — Pr ° ut > Mimoire sur Vkema- 

* Beside tne sexual differences M S t?, % ** "^ V °\ * L > P' 132 " 2 15. 
stomach of the negro diQers from that of V^iir Scemm . e ™.£T has shown that the 
form, approaching that of the ™ S^^K W * "— ^ M 

(4) Helvetius, Observations sur la memhm-nn ^^1. < • , J : 

? eloLt6e, sur leur membrane ^^^SrtoSr5S3J± m^T ^ CS < a PP el & 
in the Mim. de Pari,, 1721, p. 392-403 -C B Ah™ n SCUlm " McAa ™«.' 
tenuium hominis, Lejden, 1722, 1724. -aiDinus, Veacnptw intestinorum 



OF THE DIGESTIVE SYSTEM. 263 

mach and the large intestine. It is uninterruptedly continuous with 
both, although separated by two valvular folds, the pylorus and the 
ilieo-coecal valve, the closing of which can perfectly insulate its cavity, 
which is sometimes the case. 

Its outer circumference is uniform ; this is also the case with its 
diameter in most of its extent, and hence it is cylindrical. 

Its whole length from the pylorus to the commencement of the colon 
varies much from thirteen to twenty-seven feet, although the length 
of the body does not differ in the same proportion. 

It is about an inch in diameter when moderately distended. 

The description of the duodenum may be separated from that of the 
small intestine, as it differs from this latter in several respects. 



A. DUODENUM. 

§ 2157. The commencement of the small intestine, that portion 
directly next to the stomach, is called the duodenum from its length. (1) 

This intestine is situated in the right half of the abdomen. It de- 
scribes, a considerable arch, the convexity of which looks to the right 
and the concavity to the left. We distinguish in it three parts, a su- 
perior, which ascends obliquely from left to right and a little from 
before backward ; a middle, oblique from right to left and descending ; 
finally an inferior, oblique from right to left and ascending. 

It is attached to the gall-bladder and to the commencement of the 
transverse colon. Its upper and smallest portion is situated above, 
and the lower and largest, below the transverse colon. It is covered 
in most of its anterior face by the posterior wall of the peritoneum, 
which extends forward in this place to form the transverse mesocolon, 
surrounds it loosely, and keeps it fixed against the posterior wall of 
the abdominal cavity. 

The middle portion descends below the transverse mesocolon, and 
when this fold of the peritoneum is raised it is seen on the right side of 
the mesentery. 

The third, on the contrary, is situated on the left side of the mesen- 
tery, the upper part of which arises from it directly. It extends to the 
second lumbar vertebra, goes forward in the place where the upper 
extremity of the mesentery blends with the transverse mesocolon and 
opens into the jejunum. 

If we except its first portion, which is covered in every part by the 
peritoneum, the duodenum is protected by this membrane only on its 
anterior side ; the posterior is attached by a very loose cellular tissue 
to the posterior wall of the abdomen and directly to the organs situated 
behind it. 

(1) L. Claussen, De intestini duodeni situ ct nexu, Leipsic, 1757.— Sandifort, Ta- 
bulae inteslini duodeni, Lcyden, 1780. 



264 DESCRIPTIVE ANAT0MV. 

The middle portion descends along the concave edge of the right 
kidney and on the right side of the vertebral column to the fourth lum- 
bar vertebra. . . ' . ' ., - ., 

The inferior ascending portion is situated on the right side ot me 
vena-cava and the right renal vessels, on the left side of the aorta, be- 
hind the upper part of the root of the mesentery, the superior mesen- 
teric artery, and the great mesaraic vein. 

Its left and concave portion closely embraces the right halt ol me 
pancreas. . . 

§ 2158. The duodenum is generally broader at its origin than m 
any other part ; its concave face is corrugated, its convex face is 
smooth and tense. 

It differs from the other portions of the small intestine by its situa- 
tion and the firm manner in which it is kept in place, and also by its 
greater extent and the less regularity of its folds. 

B. MEMBRANES OF THE SMALL INTESTINE. 

§ 2159. The small intestine is covered externally in all its extent 
by the peritoneum, and, except the duodenum, it is attached to the 
lumbar portion of the vertebral column by a long fold of this mem- 
brane, termed the mesentery (mesenterium) . 

Below this peritoneal tunic is the thin muscular membrane,(l) which 
is about a third of a line thick. 

The external or longitudinal layer, although much thinner than the 
internal, with which it is very intimately united and which is never 
entirely deficient, surrounds the canal almost entirely. 

The internal layer is transverse or rather oblique, and circumscribes 
it entirely. 

The vascular membrane presents nothing remarkable. (2) 

The small intestine differs from the other portions of the intestinal 
canal principally by the arrangement of its inner or mucous mem- 
brane.(3) The principal character which distinguishes this membrane 
is the singular increase of its extent and the greater development of 
its surface, compared with that of the external membranes, especially 
the muscular and the peritoneal tunics. 

This enlargement depends on its folding from without inward, which 
gives rise to two kinds of folds, the great and the small folds. 

The great folds are termed valves (valvulce), and the small, villosi- 
ties {villi). 

(1) V. Malacarne, Sulla structura anatomica clelle intestine; in the Memoric 
delta societa italiana, vol. x., p. 27-62. 

(2) B. S. Albinus, Diss, de arteriis et venis intestine-rum hominis, Leyden, 1736. 
— J. Bleuland, Vasculorum in intestinorvm tcnuium tunicis subtilioris anatomes 
opera detegendorum descriptio, Utrecht, 1797. 

(3) Helvetius, loc. cit. — D. G. Galeati, De cribriformi intestinorum tunica ; in the 
Comm. Bonom., vol. i., 1731, p. 359-370. 



OP THE DIGESTIVE SYSTEM. 265 

Both are developed principally at the upper extremity of the small 
intestine. They diminish much in number and size from the origin of 
this organ to its termination. 



§ 2160. The valves are three lines high at the upper part of the 
small intestine. 

They have a transverse direction, and most of them occupy the 
whole circumference of the intestine, so that they form circles which 
circumscribe it. But they divide once or twice in their course, and 
also communicate with each other by oblique or perpendicular eleva- 
tions, which generally are less prominent and much shorter than 
they; three or four of them always exist between each pair of 
valves. 

They are very numerous, being only a few lines distant from each 
other. 

There are but very few at the lower part of the small intestine, but 
before entirely disappearing, they gradually diminish in elevation and 
breadth. 

They are formed only by the inner membrane and by the vascular 
tunic of the intestine, so that they cannot move themselves, but they 
are floated by the motions caused by the muscular tunic in the fluids 
within the intestinal canal. When we cut the intestine, we observe 
that they are directed towards each other, so that if we immerse the 
organ in water they cover one another like the tiles of a roof. 

Hence the term valvules, conniventes, applied to them by Kerckring ; 
but it is wrong to ascribe this discovery to this anatomist, from which 
error they have derived the name of the valves of Kerckring (vatvulaz 
Kerckringii). 

An artery and vein usually pass through the base of each valve. 

These valves delay the course of the substances in the alimentary 
canal; hence their greater development at the upper part of the small 
intestine is curious, since the fluid contained in this portion possesses 
the most nutritious particles. 

They are no less curious as a peculiar character of the human or- 
ganism. Morgagni mentions their absence in some ruminantia.(l) 
We have also looked for them in vain in many mammalia of all orders, 
even among the apes: In fact several fishes present very analogous 
transverse valves, which are often very numerous ; but they occupy 
the end of the intestinal canal in these animals, and they have no vil- 
losities. They present also this character in those reptiles in which 
we have seen them. (2) 

(1) Ep. an., xiv., p. 20. 

(2) Deutsches Archiv.fur die Physiologie, vol. iii., part ii. 



266 DESCRIPTIVE ANATOMY. 

We may then say, in order to express the preceding proposition 
more precisely, that man is the only being possessing both transverse 
folds and villosities in the small intestine, and alone presents the union 
of these two organic arrangements, which are found separately in 
other animals. In fact most mammalia and birds, as also some rep- 
tiles and fishes, present only the villosities, and but a few genera of 
the last two classes the transverse folds. 

D. VILLOSITIES. 

§2161. The villosities(l) are small thin prolongations, which arc 
generally rounded, sometimes cylindrical, sometimes conical, and ter- 
minated insensibly in a point ; finally, sometimes enlarged at their loose 
extremity ; they are attached to the mucous membrane ; hence, the 
term villous tunic (tunica villosa), often applied to it. 

The villosities cover all the inner face of the mucous membrane of 
the small intestine, being very compact at its upper part, while at the 
lower part they are more or less remote from each other. In regard to 
their form, some authors, as Galeati, admit that they are cylindrical, 
or pointed at the origin of the intestine, and conical at its termination, 
but this difference is not constant. We have always found on the con- 
trary, which agrees with the observations of Hewson, that the villosi- 
ties at the upper part of the canal are broader in proportion to their 
length, and that from their form, they resemble the valvulae conniven- 
■ tes, while as those of the lower part were thinner, elongated, and even 
sometimes longer than the preceding. They are about one quarter of 
a line long. As they are arranged very compactly, and as there are 
about four thousand in a square inch, we may estimate their whole 
number as more than a million, which is very moderate. 

When examined by the microscope, they appear formed of a granu- 
lar substance, and their surface is not perfectly smooth, although it is 
not indented. When the blood-vessels of the intestinal canal are in- 
jected, the villosities are not only more apparent and filled with injec- 
tion, but their surface is more uneven, because a vascular net- work is 
developed in it. 

When the lymphatics are injected, we see on their surface a net- 
work formed by these vessels. 

They are then composed of cellular tissue, in which are blood-ves- 
sels and lymphatics, the parietes of which are not distinct from its sub- 
stance. It has long been disputed, whether the villosities open on 
their surface or not 1 

.. <*> .^ esi ? e the F * 9 of Helvctius, Galeati, and A. Meckel, consult particularly on 
the vriloaities:-^J. N. Lieberkuhn, Defabrica ct actionc. villorum intcstindum 
tcnuium hominvs, Leyden, 1/45. — Hewson, in his Exp. inn, vol ii c xii — R A 
Hedwig Disquisitio ampullarum Liebcrkuhnii physica-microscopicd, Leiosic 1797' 
— C. A. Rudolphi, in his Abhandlungcn, &c. p. 39; ' ljCI P slc ) 1 ' y '• 



OF THE DIGESTIVE SYSTEM. 267 

Excellent observers, as Lieberkuhn, Hunter, Cruikshank, Hewson, 
Hedwig, and Bleuland, admit these openings, and assert they have 
seen them. Lieberkuhn and Bleuland think there is generally only 
one at the extremity of each villosity, rarely several. Others mention 
more, and assert they are situated in the same place. When a minute 
injection has raised, inflated, and rendered the villosities cylindrical, 
they appear spungy, and perforated at their extremity, while they re- 
main smooth and united on the sides. We cannot consider these open- 
ings as arising from accidental ruptures, since they are empty and en- 
tirely separated from each other, and they also occur only in determi- 
nate points, while in ruptures of a part, the vessels of which are filled 
with injection, we should necessarily see this injection. Cruikshank 
and Hunter have counted twenty of these openings in the villosities 
which were not injected, but only gorged with chyle. 

The arguments of Rudolphi who has never seen these openings 
do not refute the assertions of the observers above mentioned. He 
does not mention Hewson at all. The diameter of the openings 
figured by Cruikshank and Bleuland, which seems too great to be cor- 
rect, may depend on some individual peculiarity, on the state in which 
the activity was at the moment of death, or even on some disease all 
which circumstances would render the openings more perceptible. 
If Hewson has not figured them in all the villosities, it may depend 
either on their diameter or on the situation of the villosities, and the 
manner in which they were lighted. 

Thus, although these openings are not necessary to explain the 
phenomenon of absorption, they seem to exist.(l) 

E. GLAND3. 

§ 2162. The inner membrane of the small intestine is covered with 
numberless muciparous glands, which differ in their size and arrang-e- 
ment. 9 & 

_ In its whole length, and on all its surface, there are very numerous 
distinct glands, which are the smallest (G. mucosa, s. crypta minima) 
and which cannot be seen without a microscope.(2) 

(1) Strictly speaking-, the question is, whether the pores of the villosities, for thcv 
must necessarily exist in every organic or inorganic substance, possess a special 
organization, so that they may be compared to a certain extent with the lachrymal 
puncta for instance. But it is what it does not seem to be, and we cannot but apply 
to m.croscopical observations, where the illusions are so frequent and difficult to avoid 
the axiom, that a negative assertion does not refute a positive one, when the latter is 
»n?K l b7 f g0 °V U i h , 0r u U , y - T h . e researches of A. Meckel, the brother of the 
Z v uLu°, Al R P dol P hls °P 1 ' 110 , n : This anatomist does not admit vessels in 
♦Km 7™ i ♦> m1 f 3 } l lne > a . nd thl r nks thatthe injection which penetrates into 
t ! m 'n i n3 " desthr{ ? u g' 1 h t he P arietes ofthe arterial terminations, to be distributed in 
the cellular tissue which forms them. Farther, he has found, contrary to the asser- 
tion ot all his predecessors, that the villosities are always flattened layers, most 
generally turned on their axes, and often folded on each side, so as to form a semi- 
canal or a groove, which arrangements vary infinitely, and by which he explains the 
different appearances described by authors before him. F. T 

(2) Oraleati, loc. cit.— Lieberkuhn, De viUis inlesUnorum. 



268 DESCRIPTIVE ANATOMY. 

Others are much larger, and divided into two classes, the solitary 
(G. solitaries) and the agglomerate (G. agminate). The first are 
termed also the glands o/\Br«nwer,(l) and the others the glands of 
Peyer.(2) 

The glands of Brunner are seen particularly at the commencement 
of the small intestine, especially in the duodenum, where they appear 
in the form of small, flat, rounded, lenticular bodies, at most one line in 
diameter, situated on the posterior face of the mucous membrane, and 
which open into the cavity of the intestine by broad orifices. 

When these simple glands are very large, and project considerably 
above the inner face of this portion, or the other parts of the canal, it is 
always from a morbid state. 

The glands of Peyer rarely exist except in the ileon, where they en- 
large much from the commencement to the end of the intestine. 

They form about thirty masses, which are generally oblong and 
rounded, seldom triangular or almost square, the longitudinal axis of 
which is parallel to that of the intestinal canal ; they are rarely more 
broad than long, and they do not exist on the side of the intestine cor- 
responding to the mesentery, but on the lateral portions, particularly 
the anterior. 

They are not prominent, or at least project but little above the sur- 
face of the intestine, and they are distinguished only by the intestine 
being less transparent in the points they occupy. They form on the 
posterior face of the mucous membrane, a thin layer, which is com- 
posed of bright, transparent, rounded, and slightly depressed points, 
and of darker edges in the spaces between these points. 

They vary in length from some fines to three or four inches ; they 
are about nine lines broad. 

At the upper part of the ileon they are five or six inches distant from 
each other ; but at the lower part, and near its termination, they are 
almost blended with each other, and sometimes form in the loose por- 
tion tf the edge of the small intestine, an almost uninterrupted layer 
eight inches long. 

F. FUNCTIONS OF THE SMALL INTESTINE. 

§ 2163. The inner membrane of the small intestine secretes the in- 
testinal mucus (mucus intestinalis) and the intestinal liquid (liquor en- 
tericus), which probably form one and the same fluid, partially favor- 
ing the assimilation of the alimentary substances by its action upon 
them, and also their progress by the lubricating layer on the surface 
of the intestine. This progress is caused by the muscular tunic, which 
alternately dilates and contracts from the commencement of the small 
intestine to its termination, so as to send forward its contents in the 

(1_) Brunner, Glandultc intestini duodeni, s. pancreas secundarius, Frankfort, 
171o. 
('-) C. Pcyer, Deglandulis intcstiiwrum, Schafhousc, 1677. 



OF THE DIGESTIVE SYSTEM. 269 

same direction. In passing through the small intestine, but particu- 
larly in the duodenum, and from the influence of bile, aided by that of 
the pancreatic juice, the chyme is separated into two portions, the 
chyle {chylus), a whitish fluid, similar in its chemical properties to the 
blood and the facal matter {faces).. The chyle is absorbed by the vil- 
losities of the intestine, whence it passes into the lymphatic vessels, and 
probably also into the meseraic veins. The feces proceed into the 
large intestine. 

in. large intestine. 

§ 2164. The large intestine (intestinum crassum, s. colon) differs from 
the small intestine in its situation and attachments, form, length, 
breadth, and the arrangement of its tunics. 

A. SITUATION AND ATTACHMENTS. 

§ 2165. The. large intestine describes an arch, the direction of which 
is from below upward, then goes transversely from right to left, and finally 
from above downward, begins at the lower extremity of the small in- 
testine, and terminates at the anus. It commences at the right iliac 
region, but not always in the same point. This point is generally 
situated at the upper extremity of the anterior face of the right iliacus 
muscle, between this and the psoas muscle ; sometimes, also, it occurs 
much lower, and sometimes much higher, before the right psoas 
muscle. The small and the large intestine are intimately attached in 
this place to the iliacus muscle by a short cellular tissue, and the first 
is there continuous from within outward, and from below upward with 
the second. 

The higher, that is, the more abnormal the union between the two, 
the more similar the arrangement to that in the fetus. 

At the point of union the commencement of the colon presents a 
prominence which extends below its terminating extremity, and is 
termed the ccecum, and the ccecal appendix. 

B. DIVISION OF THE LARGE INTESTINE. 
A. ILEO-COLIC VALVE. 

§ 2166. The small intestine is suddenly continuous .with the large, 
at the point mentioned, so that it enters there at an acute angle from 
below upward, from left to right, and from within outward, for about an 
inch, and there forms a prominence termed the ileo-colic valve, (1) or 
the valve of Bauhin (valvula ileo-colica, s. Bauhini). This valve is 

(1) L. Heiater, Dc valvula coli, Altdorf, 1718.— J. N. Lieberkulm, Dc valvula. 
coli, Leyden, 1739.— Haller, De valvula coli, Gottintren, 1742.— J. M. Rcederer, Dc 
valvula coli, Straeburg, 1768. 

Vol 111 .35 



270 DESCRIPTIVE ANATOMY 

composed of two layers, a superior, generally a little narrower and al- 
most horizontal, which forms, nearly a right angle with the ascending 
portion of the colon, and an inferior, which is broader, and describes a 
more acute angle with this same portion. 

Between the two layers is a transverse and oblong opening, which 
is the slightly contracted orifice of the small intestine. 

Each is formed by the inner membrane of the vascular tunic, and the 
circular fibres of the muscular membrane of the large and the small 
intestine which are turned over in this place, while the longitudinal 
fibres, and the peritoneal tunic, which do not fold, pass like a bridge 
from the loose portion of the small intestine on the large. The muscu- 
lar tunics of the two intestines are united with each other at their ex- 
ternal face by mucous tissue, and when we consider only the valve, 
they form its most internal part or its centre. When we carefully de- 
stroy the cellular tissue which unites them, the valve entirely disappears, 
the small intestine opens directly into the large by a broader orifice than 
the rest of its caliber, in the form of a trumpet, and then the union of 
the two intestines still more resembles that of the esophagus with the 
stomach, since in both places the line of demarkation is evidently indi- 
cated by a very evident difference in the texture of the inner membrane, 
by the greater size of the lower portion into which the other opens, 
and by its projecting above this latter, giving rise to a cul-de-sac. 

§ 2167. In the normal state the. ileo-colic valve separates the small 
from the large intestine, so as to allow, the substances contained in the 
first to pass into the second, but entirely preventing them from reas- 
cending from the latter into the former. This effect depends both on 
the action of the muscular fibres and.the form of the valve. ■ 

B. CECUM AND VEBMIFOHM APPENDIX. 

§ 2168. The portion of small intestine which passes beyond the 
colon, (§ 2166) is composed of the ccecum (intestinum ccecum), and of 
the vermiform appendix (appendicida vermiformis) y (\) which originally 
form but one, and which do not begin to be distinct until after the early 
years of life. 

§ 2169. The ccecum is elongated, triangular, and as large as the 
rest of the colon. It extends from an inch to an inch and a half beyond 
the terminating portion of the small intestine. The muscular fibres 
in particular, are very irregular, and very much interlaced near its 
closed extremity. It is terminated by a blunt summit, of which the 
vermiform appendix is the prolongation ;(2) the latter, however, rarely 
leaves its centre, but arises from its left side a little posteriorly. It is 

(1) J. N. Lieberkuhn, Dc ralvnla coli et u.tu processus tcrmicularis Leyden 
1739.— J. Vosse, Deintestinoccecoejusqucappendicevcrmiformi, Gotting-e'n 1749 — 
Van den Busch, Dc intcstino coxa cjusque processu vcrmiformi, Gottingen 1814 

(2) Louyer Villermay, Observations pour scrvir a Vhistoirc des inflammations dc 
I'appcndkedu concum; in the Archiv.'gtmr. dc mtdccinc, vol. v. p. 246. 



OP THE DIGESTIVE SYSTEM. 271 

the narrowest part of the alimentary canal. A small fold of peritoneum 
unites it to the lower extremity of the mesentery, and to the spermatic 
vessels which are situated below it. 

This appendix is generally about three inches long. 

Excepting its orifice, which is a little broader than the rest, and tun- 
nel-shaped, its breadth is nearly equal in every part, and is about two 
lines. It is terminated in a blunt summit. A transverse fold, a kind 
of valve, sometimes, but not always, separates it from the ccecum.(l) 

Near the end of the ccecum, the three bands which form the longi- 
tudinal muscular layer of the large intestine, unite to form a thinner 
and uniformly expanded membrane, which is extended on the vermi- 
form appendix, where it assumes the same arrangement. 

§ 2170. The parietes of this appendix are as thick as those of the 
large intestine, and its inner membrane forms, from its great number 
of large and extremely compact muciparous glands, a very complex 
net-work, similar, although much larger than that formed by the ine- 
qualities of the inner face of the rest of the colon. 

Not unfrequently, although not always, this inner face also presents 
larger transverse prominences, folds similiar to those at the orifice of 
the appendix. 

The vermiform appendix is not always situated exactly in the same 
place ; it sometimes descends almost entirely into the pelvis, the edge 
of its mesentery opposite to that which adheres to it, being loose. 
Sometimes it goes upward, passing under the commencement of the 
large intestine. Sometimes then it assumes this ascending direction in 
its whole extent, and sometimes its lower extremity again curves 
downward in a greater or. less extent. 

C. ASCEND1KG COLOK. 

§ 2171. The large intestine begins with the right or ascending 
colon (I. colon dextrum, s. ascendens), which is its shortest portion, as- 
cends before the right kidney, With which it is intimately united by the 
right lumbar meso-colon, and extends to the anterior part of the lower 
face of the right lobe of the liver. In this place it describes a right or 
an acute angle under the base of the gall-bladder, with which it has 
normally no connection, goes to the right, and is continuous with the 
transverse colon. 

D. TEAKSVEESE COLOK. 

§ 2172. The transverse colon (colon transversum) is attached to the 
posterior wall of the abdomen by a much broader fold of the peritoneum 
than that of the preceding, termed the transverse meso-colon ; it is situ- 
ated below the stomach, with which it is always more or less intimate- 

(1) Morg-agni, Adxcrs. anat. Anim. XI V.— Bonazzoli, Observ. in intesi. ct renibus 
hubilce ; in the (Somm. Bonon., vol. ii. p.. 2. p. 138. 



272 DESCRIPTIVE ANATOMY. 

ly united by the great epiploon, and always descends more or less be- 
fore the iblds of the small intestine, usually to the umbilical region, 
sometimes even into the small pelvis. It is always much longer than 
the ascending colon, and sometimes very much exceeds it in size, and 
then describes several circumvolutions. It extends from the right to 
the left side. Its two extremities, are intimately attached to the duo- 
denum by the meso-colon, which is much shorter in these two parts 
than in its centre. On the centre of the anterior face of the right kid- 
ney, and at the lower extremity of the spleen, it is continuous with the 
descending colon, describing either an arch, or a more or less acute and 
sometimes a double angle. 

E. DESCENDING COLON. 

§ 2173. The descending colon (I. colon descendens) extends from 
the lower extremity of the spleen to the pelvis, passing along the lower 
half of the' anterior face of the left kidney, then the quadratus lumborum 
muscle, and finally the upper and inner part of the left iliacus muscle. 
It is continuous with the rectum before the right sacro-iliac symphasis. 

It is attached to the posterior wall of the abdomen, above by a short, 
and below by a very large fold of the peritoneum. 

This lower part projects more or less forward, and to the right, and 
sometimes adheres to the ccecum ; it describes a curve, hence it is called 
the S, or sigmoid flexure of the colon (flexura sigmoidea, s. iliaca, s. 
S. romanum). 

T. RECTUM. 

§ 2174. The rectum (i. rectum) is the last portion of the intestinal 
canal, and it opens externally by the anus. It begins at the lower 
extremity of the colon, is attached to the left half of the anterior face of 
the sacrum in a slight portion of its upper extremity, by a short fold of 
the peritoneum, termed the meso-rectum, and in the rest, simply by cel- 
lular tissue ; it goes from left to right, and from above downward, so 
long as it is surrounded by the peritoneum, and does not begin to de- 
scend in a straight line until this membrane leaves it. 

Sometimes it descends in the pelvis on the right, and not on the left 
side of the sacrum. In one case of this kind observed by us, the great 
inferior left curve or the sigmoid flexure of the colon, advanced very 
much toward the right, united very intimately at its centre with the 
commencement of the ascending colon, and was attached in this man- 
ner to the right side. Its ascending and descending portions were also 
attached and separated a little from each other inferiorly. Below this 
point, the commencement of the curve and that of the rectum were also 
united by a fold of peritoneum, whence there was a considerable de- 
pression, which might easily receive a portion of small intestine several 
inches long, and thus give rise to an internal hernia. 



OF THE DIGESTIVE SYSTEM. 273 

Although we may justly consider the rectum as the lower part 
of the large intestine, the rectum differs from it in several- respects. 
In fact : 

1st. It is almost always much broader, and in this respect it ex- 
ceeds more or less the other portions. 

2d. The peritoneum covers it only in its upper region ; even 1 here 
it covers, in most of its extent, only its anterior face, and forms no epi- 
ploic appendages on its surface. 

3d. Its muscular fibres are much stronger, and the longitudinal 
layer surrounds it in every part. 

The inner membrane is also smooth and filled with simple mucipa- 
rous glands, but these glands are smaller and fewer.(l) 

(1) The recto-vesical operation for stone, introduced by Sanson, which becomes 
more extensively known every day (J. L. Sanson, Dcs moyens de parvenir d la vessie 
par le rectum, Paris, 1817), requires a more detailed description of the anatomical 
relations of the rectum. Taken as a whole, this intestine extends from the upper 
strait of the pelvis to the anus. Its direction is at first a little oblique from left to 
fight, and it curves toward the lower part of the cavity of the pelvis to go from 
behind forward, under the bladder, to the level of the prostate gland, below which 
it again curves from above downward, and a little from before backward. We may 
then consider it formed by three parts separated by these two curves, and distinct 
in their situation and structure, and the nature and importance of their connections. 
The first or superior is directed from above downward, and a little obliquely from 
left to right ; it extends from the end of the sigmoid flexure of the colon to the place 
where the intestine leaves its peritoneal envelop, and curves to go below the bladder : 
it forms more than half of the rectum. It is tortuous, loose, smooth, covered by the 
peritoneum, and attached loosely to the posterior wall of the cavity of the pelvis by 
a fold of this membrane. The second or central part is included between the two 
curves, and is about three inches long ; its direction is oblique from above down- 
ward and from behind forward ; it is slightly curved in the same direction, is fixed 
and immovable, and constantly corresponds posteriorly to the lower part of the sa- 
crum, the coccyx, and the base formed by the ischio-coccygei muscles : forward to 
the base of the bladder, from which it is separated downward and outward by the 
seminal vesicles and the vasa deferentia, and still lower by the prostate gland : 
finally, on the sides to an abundance of cellular tissue. It differs in structure and 
organization from the upper portion, being wholly destitute of the peritoneum, ex- 
cept sometimes at the highest part of its anterior face, when the bladder is consi- 
derably retracted ; its muscular coat also is much thicker, and formed of much 
stronger and more numerous longitudinal fibres; it is every where surrounded by 
a cellular tissue, compact only below the prostate gland, loose and very abundant in 
the rest of the circumference of the intestine. Finally the lower portion of this 
latter commences below and on a level with the prostate gland, and terminates at 
the anus. It varies in length from one inch to an inch and a half. It is broader 
above than below. Its direction is oblique from above downward, and a little from 
before backward. Near its origin it is every where surrounded by an abundant 
cellular tissue, except forward, where it corresponds to the prostate gland ; in the 
rest of its extent it is enveloped by the sphincters. Its structure differs much from 
that of the other portions. In fact, when the rectum curves a second time below 
the prostate gland, its fleshy tunic, which is very thick, and composed of numerous 
longitudinal fibres, terminates suddenly; the mucous membrane alone extends 
to the skin, surrounded by the round muscular fibres of the sphincters, which meet 
and form a kind of ring, much thinner at its origin than on the side of the skin, 
where it becomes much thicker, and gives rise-to two caudiform prolongations, of 
which the anterior, the longer, goes toward the bulb of the urethra, arid there blends 
with the bulbo-cavernosus muscle, while the posterior proceeds to the coccyx. This 
muscular ring is covered internally by the end of the mucous tunic of the intes- 
tine, is united forward and upward to the prostate gland, and is adapted in every 
part to very abundant and fatty cellular tissue. Thus the upper portion of the 



274 nr.sciiirTiVE anatomy. 



§ 2175. The largo intestine is not uniformly cylindrical like the 
other sections of the intestinal canal, but presents numerous elevations 
and depressions, which render its surface uneven. In fact the longi- 
tudinal fibres are there united in three bands separated by spaces, and 
the muscular membrane considered generally is shorter than the inner 
tunics. Hence it follows, that when the cavity of the large intestine 
receives the residue of digestion, it forms between the three bands three 
series of rounded bursse which vary in size, and are termed cellules 
(cellules, s. haustra). 

These bursse are all similar but are not perfectly alike, and are no 
where arranged symmetrically. Their origin from the cause men- 
tioned proved by the fact that on cutting the bands the inequalities 
disappear in. the place corresponding to the incision, and the canal 
there possesses a perfectly cylindrical form. 

D. LENGTH AND BREADTH. 

§ 2176. The length of the large intestine is about five feet, and its 
breadth when moderately distended varies between an inch and a half 
and two inches. 



E. ARRANGEMENT OF THE TUNICS. 
A. PERITONEAL COAT. 

§ 2177. In most of its extent, especially in its ascending and de- 
scending portions, the large intestine is covered by the peritoneum only 
forward and on its sides and not on its posterior face, which is attached 
to the adjacent parts only by very loose cellular tissue. The trans- 
verse portion, on the contrary, is every where surrounded by the peri- 
toneum. From the loose portion of the peritoneal coat arise the 
epiploic appendages (appendicces epiploicce). 

B. MUSCULAR MEMBRANE. 

§ 2178. The muscular membrane of the large intestine, except 
the rectum, is thinner even than that of the small intestine. It is 
composed, as in every other part, of longitudinal and of transverse 
fibres. 

rectum is movable, and covered by the peritoneum, while the middle and inferior 
parts, forming together about at least four inches, arc surrounded in every part bv 
an abundance of cellular tissue, and are attached, but have no peritoneal envelop 

F. T.' 



OF THE DIGESTIVE SYSTEM. 27S 



The longitudinal fibres distinguish the large intestine from all the 
other portions of the intestinal canal in this respect, that generally 
speaking, they are united in three bands, situated at nearly equal dis- 
tances from each other, about from four to six lines broad, which gra- 
dually increase in thickness from the circumference to the centre, une 
of these bands is situated posteriorly, and corresponds to the point 
where the intestine is kept in place by the peritoneum ; the second is 
anterior, and proceeds in the middle portion below the insertion of the 
epiploon : the third occupies the inside of the ascending and the de- 
scending portion, and the lower side of the transverse portion, w her f, 11 
is perfectly loose. All terminate at the vermiform process and m tne 
longitudinal fibres of the rectum. . 

The thickness of the muscular tunic of the large intestine is dimi- 
nished by the insulation of its longitudinal fibres. . 
The bands are much thicker the greater the number of these fibres, 
• from which they arise. . 

They are about half a line thick, so that the thickness of the mus- 
cular tunic is considerable in the parts which correspond to them. _ 
' We also find at intervals between these three bands several distinct 
fasciculi of longitudinal fibres ; and in subjects where the muscular 
system is very much developed, the large intestine is entirely sur- 
rounded by a layer of these fibres, always arranged, however, so that 
the intermediate fibres are much weaker than the three bands. 

The circular fibres constantly surround the whole of the intestine, 
but they are much feebler than the longitudinal. 

C. MUCOUS MEMBRANE. 

§ 2\79 The mucous membrane is perfectly smooth when consi- 
dered superficially, but when examined attentively we observe that it 
is uneven, from numerous small, rounded, oblong, compact depressions, 
similar to the points of pins. These depressions give it a shaggy or 
honey-comb appearance, as is seen on the inner face of the mucous 
membrane of the stomach.(l) The elevations between them occupy 
a greater space than they, and may be considered as corresponding to 
the villosities of the small intestine. 

The arrangement of the inner membrane of the two sections of the 
intestinal canal differs extremely at. the place where they unite and 
these two sections are separated by a very distinctive of demarkation, 
although uninterruptedly continuous with each other. 

We cannot determine whether the function of these depressions is to 
secrete, any more than the other parts. We know, however that they 
are not surrounded by a substance different from that of the rest ,of 
the mucous membrane ; but this latter appears more thin and more 
transparent in these points than in the intervals between them. 

(1) This has already been observed by Hcwson (Exp. ing., pt. »., p. 174). 



27G DESCRIPTIVE ANATOMY. 

The mucous membrane of the large intestine presents a great num- 
ber of muciparous glands, which are distinct or united in pairs or in 
triplets, and situated near each other. These glands represent small 
depressions with a more or less elevated edge. They are very evident 
in intestines hardened by alcohol, because then the inner membrane is 
contracted, and assumes a brownish "color. They are formed partly 
by the union of several of the smallest glands.(l) 



F. MUSCLES OF THE ANUS. 



§ 2180. The lower extremity of the rectum is subject to the in- 
fluence of the will, and is moved by several muscles, the sphincters, 
the levatores ani, and the transversi perinei muscles. We shall de- 
scribe here only the sphincters, referring the history of the others to 
the chapter on the genital organs, with which they are more intimately 
connected than with the anus. 

§ 2181. The anus has two sphincters, an internal and an external, 
both of which result from a greater development of the circular fibres 
of the rectum. 



A. SPHINCTER ANI INTERNUS. 



§ 2182. The sphincter ani inlernus muscle proves very evidently 
the origin above mentioned ; for the longitudinal fibres of the rectum 
are deficient from three to four lines, the circular fibres become redder 
and thicker, have the form of a flattened ring, which extends beyond 
the longitudinal fibres. This ring is three or four lines high and about 
two lines thick, and it is situated directly under the skin. 



n. SPHINCTER ANI EXTERNUM. 



§ 2183. The sphincter ani externus muscle is much stronger than 
the preceding, and although a distinct muscle, exactly surrounds it. 
It is situated under the skin, to which it adheres very intimately. It 
is thin and flat ; its internal fibres are less arched than the external, and 
the anterior and the posterior unite at an acute angle. Its anterior 
and posterior extremities are pointed. 

The posterior extremity is attached to the posterior face of the last 
piece of the coccyx either directly or by a compact cellular tissue. 

The anterior blends with the transversus perinei muscle, and 
usually also in man with the posterior extremity of the bulho-caver- 
nosus, in the female with the constrictor vagina; muscle. But some- 
times also it terminates in the perineum, either by fleshy or by tendi- 
nous fibres, and does not extend to either of these two muscles. 

(1) Galcati, loc. cit., fijr. 3 



OF THE DIGESTIVE SYSTEM. 



277 



In the male it is more oblong, and its greatest diameter extends 
from before backward ; in the female it is more circular, and at its 
anterior part it is broader and stronger. These differences undoubtedly 
depend on those which exist in. the two sexes in the form of the pelvis 
and the external organs of generation. 

G. FUNCTIONS OF THE LARGE INTESTINE. 

§ 2184. The large intestine absorbs the small quantity of nutritious 
substance still contained in its contents, and sends the rest toward the 
anus. In this course the foeces gradually become harder and more 
solid. The action of the muscular membrane finally expels them, 
overcoming the resistance of the sphincters with or without the con- 
currence of the will. This expulsion always occurs periodically. 



B. DIFFERENCES DEPENDING ON DEVELOPMENT. 

§ 2185. Of all the parts in the abdominal cavity the intestinal canal 
is formed first ; its mode of development and the changes in its situa- 
tion, form, and volume, present equally remarkable phenomena.(l) 

A. MODE OF DEVELOPMENT. 

§ 2186. In respect to the mode of development one part is most in- 
timately connected With the formation of the whole fetus, but particu- 
larly with that of the intestinal canal, and must consequently be men- 
tioned first: we mean the umbilical vesicle (vtsicula inlestinalis, s. 
umbilicalis). It is a small, moie or less rounded pouch, situated be- 
tween the chorion and the amnion, and is probably much larger in 
proportion to the fetus -the more recent the period of conception. It is 
even greater than the fetus during the early periods of gestation, and 
we have reason to think that it is always formed before it. It extends 
first to the anterior face of the body of the fetus, which rests directly 
upon it. But gradually and even early in the first month of gesta- 

(1) C. P. WolfT, De formationc intestlnorum ; in N. C. Petrop, vol xii., p. 1768. — 
Oken, Anatomisch-physiologische Vntersuchungen, angestelU an Schweinsfotus, 
Schiccinsem.br yonen und Hundscmbryoncn zur Losung des Problems uber das A'u- 
belbldschen, &c, in Oken and Kieser, Beylragen, Hamburgh, 1806, 1807. — J. F. 
Meckel, Abhandlungcn aus dcr menschl ichen und vcrgleickenden Anatomie, Halle, 
1806.— Id., Bcytragcn zur vcrgleickenden Anatomie, Halle, 1808, vol. i., pt. i., no. 5. 
— Id., Leber die Divertikel, in Rcil, Archiv. fur die Physiologic, vol. ix. — D. Kieser, 
Der Lrsprung des Darmkanas aus dem Nabelbltschcn, Gottingen, 1810. — Hoech- 
stetter and Emmert, Ucber das Nabelbldschen ; in Reil, Archiv. fur die Physiologic, 
vol. x.— Fleischmann, Leichenqfnungen, Erlangcn, 1815, p. 1-75.— J. F. Meckel, 
Sur la formation du canal intestinal dans les mammifcrcs cl en purticulier dans 
riuninne; in the Journ. compl. du diet, des sc. med., vol. ii., p. 119 and 289. — L. 
Rolando, Sur la formation du canal alimentaire et des vise eres qui en dependent ; 
in the Journ. compl. des sc. vied., vol. xvi., p. 53. 

Vol. III. 36 



278 DESCRIPTIVE ANATOMY. 

tion, it diminishes much, and is situated farther from the fetus, so that 
in the second month it is on the outside of the umbilical cord. 

Do the parietes of the umbilical vesicle and the intestinal canal pri- 
mitively communicate 1 Several anatomists of great merit(l) think 
that this communication is demonstrated neither in the fetuses of the 
mammalia generally nor in that of man in particular. The following 
facts, however, render this opinion very probable : 

1st. The analogy with birds, reptiles, and cartilaginous fishes, to 
the vitelline membrane of which the umbillical vesicle corresponds 
perfectly,(2) and in which it is proved that the communication in dis- 
pute exists at all periods of fetal existence. 

2d. We sometimes perceive in very young fetuses a canal which 
goes across the umbilical sheath, from the vesicle to the abdomen, and 
by which we can at pleasure empty the vesicle of this fluid, and fill it 
again. (3) 

3d. We always find in the fetus, until the commencement of the 
fourth month, blood vessels which go from the mesentery to the um- 
bilical vesicle, unite first on this latter, but gradually extend only to 
the anterior wall of the abdomen, and finally die, and are ruptured or 
entirely effaced. These are the omphalomesenteric vessels (vasa om- 
phalo-mesaraica), comprehending an artery and a vein, which arise 
from the mesenteric vessels. (4) 

These vessels also exist in birds, where they go to the yolk, pro- 
ceeding along the vitelline canal. 

4th. The intestines are at first very near the umbilical vesicle, and 
are situated out of the abdomen in the umbilical sheath, which at this 
period really makes part of the abdominal cavity .(5) 

It is not unfrequent, proportionally speaking, to find in the full grown 
fetus a canal which extends from the intestine to the umbilicus, which 
opens in this latter place, and is always attended by the omphalo- 
mesenteric vessels. (6.) 

It is then very probable, though not certain, from all these facts, that 
the umbilical vesicle and the intestinal canal originally communicate. 
There are, however, others which really demonstrate the existence of 
this communication. 

Thus we have mentioned above a human fetus five lines long in 
which we saw distinctly a filament attached to the umbilical vesicle 

(1) Emmert.— Hoeschstetter.— Cuvier, Ann. du Museum, vol. iii. 

(2) Needham, De form, faetu, London, 1667, p. 79.— Blumenbach, Spec. pkys. 
comp. inter anim. cat. sang. ov. et viv., Gottingen, 1789, p. 11. — Scemmerrin°- in 
Haller, Grundriss der Physiologie, vol. ii., p. 799, 800. 

(3) Hunter, Anatomhche Beschreibung des schwang. Uterus, p. 68. 

(4) Meckel, Handbuch der pathologischen Anatomie, voL i., p. 563.— We have 
since verified this remark in at least ten fetuses of this age. 

(5) Meckel, Abhandlungen, 1806, p. 301.— Oken, Beytrdge, 1806, ch. ix. 

(6) We have collected, in the first volume of our Hand, der Path.. Anatomie all 
the known cases of this anomaly, one of which we observed and described (Reil 
Archiv.fur die Physiologie, vol. ix). " v ' 



OP THE DIGESTIVE SYSTEM. 279 

and extended to the intestine, and we have figured this communication 
as it exists in fetuses of sheep and co\vs,(l) since admitted by Bojanus 
also in the fetuses of sheep.(l) 

Men, however, of high authority, doubt it. Emmert, Hcechstetter, 
and Cuvier, assert that there is no continuity of substance between the 
two organs, and that the communication existing between them, is es- 
tablished only by the omphalo-mesenteric vessels. In fact, they admit, 
beside these vessels, a third filament, extended between the vesicle and 
the intestine, but they do not consider it as a canal of union, but only 
as a simple, prolongation of the peritoneum. The following are the ar- 
guments in support of their opinions : 

1st. The impossibility of passing water or any other fluid from the 
vesicle into the intestinal canal. (3) 

2d. The great difference between the white and thick substance of 
the alimentary canal, and the thin reddish membrane of the vesicle, and 
also the pellucid and delicate membrane which unites these two or- 
gans, and accompanies the omphalo-mesenteric vessels.(S) 

But we may reply to the first objection, that the phenomenon on 
which it rests depends perhaps on the narrowness of the canal, and 
also on the thinness of the vesicle, and demonstrates at most the ab- 
sence of a hollow canal of communication, the admission of which is 
not absolutely necessary, since the intestinal canal of several animals 
is solid at intervals, in the normal state. 

The second objection also loses its weight, when we consider that 
the allantoid membrane and the urachus vary at least as much from the 
bladder, and we observe as great, or even greater constant differences 
between different parts of the same system. This remark is more rea- 
sonable, since we have found the opening of the communication great- 
est in sharks, where the differences between the vitelline membrane 
and the intestinal canal were most distinct. Farther, the differences 
are also considerable in the cases last mentioned. 

We think then that we must at present admit a continuity of sub- 
stance between the umbilical vesicle and the intestinal canal, without 
pretending to decide if the cavities of the two organs open into each 
other. 

From the analogy of the development of the intestinal canal in the 
fetuses of birds, this canal'is formed in the following manner. The 
vitelline membrane, which is at first in direct contact with the vertebral 
column, begins by forming a small prominence on each side, so that 
originally, the intestine, which has the form of a groove, opens anteriorly. 

(1) Muller, De genitalium evolutione, Halle, 1815, fig. 1-2, p. 11. 

(2) Sur la vesicule ombilicalc du foetus de brebis ; in the Journ. compl. du diet, des 
sc. med., vol. ii., p. 84. — Dutrochet, Recherches sur les enveloppes du fcelus ; in the 
Mem. de la soc. med. d'dmulation de Paris, 1816; and a note to the Reflexions du 
professeur Emmert sur la vesicule ombilicale, in the Journ. compl. des sc. med,, vol. 
ii., p. 369. 

(3) Emmert, in Reil, Archivfur die Physiologic, vol. x. p. 52. 

(4) Emmert, loc. cit., p. 75. 






280 DESCRIPTIVE ANATOMT. 

This groove gradually forms, by the increase of its parietes, from be- 
hind forward, from above downward, and from below upward, to the 
place where the cavity of the intestine communicates with the vitelline 
sac by the vitelline canal, the diameter of which always diminishes (1) 
Oken's opinion, that the intestinal canal should be considered as a kind 
of excrescence of the umbilical vesicle, which enters already formed 
into the abdomen from above and from below, is less probable, and is 
unsupported by facts. 

§ 21S7. Does the intestinal canal always communicate with the 
umbilical vesicle in one determinate point % "What is this point 1 

First, this canal is continuous with the vesicle by its anterior edge, 
but very probably the point to which the communication is finally con- 
fined, always corresponds to a determinate place, although it may vary 
in a certain extent. 

Two such points have been mentioned. Oken thinks it is the point 
of union between the large and small intestine. He considers the ver- 
miform appendix and the ccecum as the result and the remains of this 
communication. (2) In this view of the subject, the umbilical vesicle in 
collapsing, and the intestinal canal on descending deeply into the ab- 
domen, produce a contraction, a kind of neck, the parietes of which ap- 
proach, and are finally blended. This separates the intestine from the 
umbilical vesicle. The canal then enters into the abdominal cavity, 
where the situation of the intestines, hitherto parallel, necessarily 
changes, so that the anterior joins the neck at an angle, and the 
neck becomes a prolongation of the posterior, which preserves its 
former direction. Hence, according to Oken, the upper intestine seems 
to penetrate into the lower, the angle of union becomes the ileo-ccecal 
valve, and the neck gives rise to the ccecum and its vermiform appen- 
dix. But, 

1st. We do not see why the contraction of the intestine, and their 
entrance into the abdomen, necessarily result in causing the upper part 
of the intestine to enter into the lower, and form a vermiform appendix. 
This is still less probable, inasmuch as the ccecum and the ileo-colic 
valve are rarely deficient in man from a primitive deviation of formation, 
while ihay are normally absent in many mammalia provided with an 
umbilical vesicle ; while others, in whom the ccecum is very large, 
have no vesicle. The great differences in 'the length and structure of 
the ccecum, render Oken's opinion very improbable. It is even more 
probable, on the contrary, that the consequence of such a formation 
would be a simple uninterrutped canal. 

(1) Wolff demonstrated long- since the manner in which the intestinal canal was 
formed by the vitelline membrane, in birds, after very correct and careful observa- 
tions, made at an useful time, that is, at a period very near its first formation. 
As Needham, Blumenbach, and Soemmering-, have demonstrated the identity of 
the vitelline envelop and the umbilical vesicle, Oken had no rig-ht to claim, as he has 
done (Beytragen zur verglcichcndcn Anatomic, IQQG.—Lchrbuch dcr Naturges- 
ehichte, 1815, p. 3), the honor of having- discovered in the envelops of the fetus ol the 
hog, that the intestinal canal is formed from the umbilical vesicle. 

(2) Loc. cii., part ii. p. 85. 



OF THE DIGESTIVE SYSTEM. 281 

2d. The cause to which Oken attributes this change does not exist; 
for the coecum is formed long before the intestines pass into the abdo- 
men, and is itself inclosed in the umbilical sheath. 

3d. If the coecum was the point where the intestine was detached 
from the umbilical vesicle, it would also be the most anterior part of the 
intestinal canal, and the nearest to the vesicle. But this never occurs, 
for we always find a fold of the small intestine before the vermiform 
appendix. Oken, it is true, has figured the contrary, according to his 
idea, that in man the intestines must detach themselves from the um- 
bilical vesicle,(l) but unfortunately this does not exist in nature. 

§ 2188. Oken's opinion is still less admissible, since arguments unite 
to render it very probable, that the communication between the intes- 
tine and the umbilical vesicle always exists in a determinate, but very 
different place from that mentioned by him. This place is in the small 
intestine, and nearer its lower than its upper extremity. 

The arguments in support of this second opinion, all of which are 
opposed to the theory of Oken, are the following : 

1st. The canals between the intestine and the anterior wall of the 
abdomen, always proceed from this point. 

2d. In one rare case, in a full'grown fetus, monstrous from the deve- 
lopment being arrested at several times, there was a real umbilical 
vesicle inserted in this canal. (2) 

3d. In this part of the canal, the vitelline canal in birds and reptiles 
terminates. 

4th. We find as the normal formation in most birds, and perhaps 
also in some mammalia, and not unfrequently as an anomaly, in this 
part, and never in any other, in man and other mammalia, a single 
rounded prolongation, varying in length and breadth, and surrounded 
by the same membranes. This prolongation, termed the diverticulum, is 
evidently a trace of the primitive canal of communication ; it is fre- 
quently attended both in the fetus and adult, with the remains of the 
omphalo-mesenteric vessels. 

Very probably, there is a period in the existence of the human fetus, 
when a similar small tubercle exists regularly, after the umbilical 
vesicle is separated from the intestine. Having found a very large di- 
verticulum attended by the omphalo-mesenteric vessels in four human 
fetuses three months old, which we had occasion to examine at nearly 
the same time, we have reason to think that the appendix continues 
regularly until this period, that is, long after the intestinal canal has 
entered the abdomen. (3) But we now renounce this opinion, although 
it has been refuted by no one. If a diverticulum really exist for some 
time as a normal formation, it disappears long before the end of the 
third month of gestation, since we have seen the coecum in the seventh 
week, although there was no trace of a diverticulum; whence itfollowSj 

(1) Loc. cit., p. 84. vol. iv. fig-. 14. 

(2) Tiedemann, Anatomic der kopjlosen Missgcburicn, tab. iv. 

(3) Handbuch dcr palhologisch.cn Anatomic, vol. i. p. 565. 



282 DESCRIPTIVE ANATOMY. 

that the omphalomesenteric vessels continue much longer than it. 
But this circumstance does not prove that the diverticulum never exists 
normally, or that Oken's opinion of the ccecum is correct. 

5th. This is the point whence the omphalo-mesenteric vessels depart 
to go into the umbilical sheath, after, and even before the intestines 
have entered the abdomen. 

6th. In all these cases one or two normal ccecums always exist in 
the part where the large intestine unites with the small. 

These different arguments seem to us to render the insertion of the 
umbilical vessels on the ileon much more probable than that of this 
organ, in the point mentioned by Oken. The diverticulum sometimes 
found, depends either on an abnormal want of energy in the formative 
power, or on the fact, that the neck of the umbilical vesicle, which per- 
haps commonly dies on the surface of the intestine, does not then dis- 
appear except in a greater or less extent. 

Although these arguments were published long since, Oken still 
continues to maintain that the ccecum is the part where the intestinal 
canal is detached from the umbilical vesicle,(l) and he lays it down as 
a principle either to oppose us, or to. support his opinion: 1st, that 
there is never but one ccecum ; 2d, that the ccecums of birds do 
not deserve this name, and are only appendages of the bladder ; 3d, 
that the ccecum exists in all mammalia, and in all birds and fishes who 
lay large eggs, while it is so small as to be invisible in a very few of 
these animals, the eggs of which are small ;(2) 4th, that this organ is 
the old vitelline canal. As these assertions are published in an ele- 
mentary work, the"y deserve to be examined, although it is easily seen 
that they are totally unfounded. 

In establishing his four laws, Oken has forgotten, 1st, of those 
mammalia which possess two ccecums, as the dama and the phasco- 
lomys ; 2d, the coexistence of the canal of the umbilical vesicle, the di- 
verticulum, and the ccecum, in the mammalia and birds ; 3d, the per- 
fect resemblance in the mammalia and birds, in the relations between 
the ccecums, the vitelline canal, the. diverticulum, and the rest of the 
intestinal canal, since the ccecums always exist on the limit between 
the large and the small intestine, while this is never true of the canal 
and the diverticulum ; 4th, the absolute want of facts, establishing that 
the intestinal canal unites with the vesicle by the ccecum, while there 
are a great number proving that it always occurs near the lower part 
of the small intestine ; 5th, the fact that the volume has no effect on 
the deficiency of the large or small size, and the other conditions of 
the ccecum, since it is very large in most mammalia, and is entirely de- 
ficient in many birds. Even when we admit that the diverticulum of 
birds is the ccecum, which, however, is impossible, his third law would 
still be refuted. His third remark, " that the ccecum exists in all mam- 

(1) Zoologie, 1815, vol. i. p. 2. 

(2) hoc. cit., p. 10. 



OF THE DIGESTIVE SYSTEM. 283 

malia, &c, but it is so small, as to be invisible in a very few of these 
animals," is difficult to understand. 

Oken has also brought forward in favor of his hypothesis : 

1st. The arrangement of the coecums in fishes, in which the vitel- 
line sac of the superior animals is divided into several culs-de-sac. 

2d. The formation of the chondropterygia,(l) in which the coecum 
arises distinctly from the vitelline sac. 

One cannot suppose that he himself believes these two arguments 
to be valid : for 

1st. Comparative anatomy demonstrates most positively, that the 
ccecums of fishes are pancreatic glands, and no one has hitherto at- 
tempted to compare them to the vitelline membrane, which also exists 
in these animals. 

2d. The ccecum of the chondropterygia is found at the end of the 
large intestine, and the vitelline canal at the end of the small intestine. 

3d. The vitelline canal is broadly open in the fetus, and exists at the 
same time as the ccecum, and is entirely separate from it. This latter 
continues during life, while the canal entirely disappears. 

We then have cause to retain our opinion, as it is also supported by 
respectable authorities, as Tiedemann,(2) Cuvier, (3) Dutrochet,(4) 
and Jaeger.(5) 

B. SITUATION. 

§ 2189. The situation of the intestinal canal varies at different 
periods, as one may conclude from the details already mentioned. Al- 
though it forms on the anterior face of the vertebral column, it is, how- 
ever, generally further from it in most of its extent, during the early 
periods of existence than subsequently. At first only a small portion 
of its upper and lower extremities exist in the proper abdominal cavity ; 
all the rest is inclosed in the umbilical sheath, which for this or for 
other reasons, is then extremely large, and should be considered as a 
prolongation of the abdomen. At first the upper and lower extremities 
of the intestinal canal extend in a straight line, side by side, and de- 
scribe an angle to communicate together; but gradually, at the 
seventh week of gestation, they proceed backward, begin to become 
tortuous, and reunite in a fold before the umbilical opening. Only the 
small intestine is tortuous, the large intestine is perfectly straight, and 
its blunt extremity, the ccecum, goes forward, but always far behind 
the anterior extremity of the small intestine. 

About the middle of the third month, the intestinal canal enters en- 
tirely into the cavity of the abdomen, where the lower part of the small 

(1) Isvs, 1818, p. 20. 

(2) Anatomic cter kopjlosen Missgeburten, p. 66. 

(3) lsis, 1818, p. 138. 

(4) Loc. cit. 

(5) Deutsches Archiv fur die Physiologie, vol. iii. p. 543. 



284 DESCRIPTIVE ANATOMY. 

intestine is the last to proceed. At this period, and sometime after, tho 
canal, especially the large intestine, varies as much as before from the 
arrangement it will afterwards normally possess. In fact, the large 
intestine is not formed of three portions, two lateral, which are perpen- 
dicular, and amiddle transverse portion, the right of which is attached 
to the organs behind it only by a short fold of the peritoneum ; but it is 
formed at first by a single perpendicular portion, attached by a long 
mesentery, to the centre of the posterior wall of the abdomen. This 
portion is gradually reflected from right to left at its summit ; it then 
descends on the right, so that the union of the groat and small intes- 
tine does not correspond to the right lumbar region until toward the 
end of the fourth month. For a long time, and until birth, the de- 
scending colon describes in the left iliac region, a greater curve than it 
does in the adult, which undoubtedly depends on the narrowness of the 
pelvis. 

The situation of the stomach differs primitively from that assumed 
by it in the adult, as it is at first almost perpendicular. The duode- 
num is detached from it, and goes directly downward and forward 
without any curve. When the liver diminishes in size, and the intes- 
tines enter the abdomen, the stomach and the duodenum gradually 
change their situation, and assume that which they afterward retain. 

C. DIMENSIONS. 

§ 2190. The intestinal canal is much shorter and narrower the 
younger the fetus is. At first it is no longer than the vertebral column, 
on the anterior face of which it is developed. It then becomes more 
extensive, and extends always in a straight line into the umbilical 
sheath, but when it becomes longer, it is tortuous, being situated in a 
narrow space. 

The small is much broader in proportion to the large intestine, the 
younger the fetus is. In this respect, the relation between them is op- 
posite to that which exists in the adult, for the small intestine, for a 
long time, is much greater than the large, and even in the full grown 
fetus the latter is frequently not at all or but little broader than it. 

On the other hand, the large intestine is much longer in proportion 
to the small, the younger the fetus is. This difference undoubtedly 
depends on the fact, that the small intestine is much shorter in propor- 
tion to the body in the early periods than in the adult. 

The ccecum and the vermiform process are at first very small, but 
soon increase considerably, so that they are proportionally much larger 
and broader than they are subsequently. They are not originally 
separated in the same manner as in the adult; the ccecum is not en- 
larged before it is continuous with its appendix; the latter is not as nar- 
row, but represents the extremity of the large intestine, which is ex- 
tended in a cul-de-sac above the ileon, gradually contractinff a little on 
itself, D 



OF THE DIGESTIVE SYSTEM. 285 

As the coecum first appears in man, the mammalia, and birds, as a 
small tubercle, which gradually enlarges, and of which there is not 
the least trace at first, this circumstance alone demonstrates that it is 
not formed in the manner mentioned by Oken, but by an enlargement 
of the large intestine. Before it appears, there is no mark of difference 
between the large and the small intestine. The ileo-cohc valve is at 
first imperfect and very small ; it however begins to appear at the 
third month of gestation, and it is perfectly developed in the full grown 
fetus. 

D. FORM. 

§ 2191. The intestinal canal during its development, differs con- 
siderably in its form, and in the arrangement of its membranes. 

We have already mentioned the differences which occur in the 
coecum, when speaking of those in dimension. We must add the 
following remarks : 

1st. The stomach is at first much longer and more rounded than 
when the development is completed. The great cul-de-sac does not 
exist originally, and it afterwards is larger than in the adult. 

2d. The outer face of the large intestine is perfectly smooth until to- 
ward the end of the fifth month. The enlargements, which are the 
sources of its great size, appear first in the transverse colon. 

Of the intestinal tunics, the internal particularly presents differences 
relative to the development of the organ. 

1st. It is more uniform in the different regions of the intestinal canal 
during the early periods of life than subsequently. Of this we may be 
easily & convinced by examining the valvules or the villosities. 

a The villosities do not appear before the third month of gestation. 
At this time they are seen first along the whole intestinal canal, in the 
form of longitudinal folds, the surface of which is indented, and which, 
like the indentations, gradually increase in number. Such is the origin 
of the villosities. When they are developed in this manner, they exist 
also in the large intestine till the seventh month of gestation, although 
their length is°less at three monihs than in the small intestine, and it 
diminishes, as well as their number, from month to month, in which 
respect, the two regions of the intestinal canal are at first perfectly 

b The valvules of the jejunum do not exist until the seventh month ; 
they are even in the full grown fetus but slightly prominent, and easily 
effaced by compression. 

These two peculiarities are curious, as they are analogous to wnat 

occurs in animals. ., 

2d The inner membrane of the stomach is thicker, and more easily 
separated from the others in the early periods of fetal existence than 
subsequently ; it is less easy to insulate it entirely in the form ot a per- 
fect sac. 

Vol. III. 3T 



286 DESCRIPTIVE ANATOMY. 



ARTICLE THIRD. 



INTESTINAL CANAL IN THE ABNORMAL STATE. 

§ 2192. The abdominal portion of the alimentary canal presents 
numerous anomalies in its form and texture.(l) 



I. DEVIATIONS OF FORMATION. 
A. PRIMITIVE DEVIATIONS OF FORMATION. 

§ 2193. The primitive deviations of formation belong principally to 
the class of those which affect the quantity. 

Among those of the first class, which essentially consist in an im- 
perfect development of the formative power, or a continuance in the 
peculiar type of the fetus, may be arranged the following, some of 
which certainly belong to this class, and others may probably be 
arranged in it. 

I. GENERAL DEVIATIONS. 

1st. Absence. This deviation of formation relates principally : 
a To the stomach, especially in acephalia vera, where the intestinal 
canal generally terminates in a cul-de-sac at its upper part, and is sel- 
dom enlarged. Sometimes a portion of the stomach also is deficient, 
particularly the pyloric valve, which is wholly or partially absent. (2) 

b. To the small intestine. It is deficient, wholly or partially, in ace- 
phalia vera, in which we often observe that the large intestine, or only 
the lower part of the small intestine exists. 

c. To the vermiform appendix, which is sometimes, though rarely, 
deficient, even when the rest of the canal is not abnormal. 

d. To the ileocolic valve, which is then simply replaced by some 
strong muscular fibres. 

e. To the large intestine. Here the anomaly exists in several de- 
grees, which are commonly attended with an imperforate anus, 



(1) A. Monro, The morbid anatomy of the human gullet, stomach, and intestines, 
Edinburgh, 1811.— A. D. Stone, A practical treatise on the diseases of the stomach, 
and of digestion. London, 1816.— T. A. Hare, View of the structure, functions, and 
disorders of the stomach and alimentary organs of the human body, London, 1821. 
— G. Law, Observations on derangements of the digestive organs, and some views 
of their connection with local complaints, Edinburgh, 1821.— Scoutctten, De I'ana- 
tomie pathologique enginiral et de celle du canal digestif en particulier, Paris, 
1822.— Andral, Recherches sur I' anatomic pathologique du canal digestif, Paris, 

(2) Fltischmann, Lcichenofungen, p. 100-102. 



OF THE DIGESTIVE SYSTEM. 267 

(atresia ani), because it usually attends this last deviation of forma- 
tion. 

Very rarely the large intestine is entirely deficient, existing only as 
a small appendix in the form of a cul-de-sac of the small intestine. 
Next in respect to frequency, come those cases, in which a small por- 
tion of the large intestine is deficient, so that the communication be- 
tween the large and small intestine is uninterrupted; finally, that where 
the large intestine is developed to the entrance of the pelvis, but where 
there is no rectum. Sometimes the rectum partially exists, but it ter- 
minates in a cul-de-sac, and the space between it and the lower extre- 
mity of the colon is also closed in a cul-de-sac. 

In this case the rectum sometimes opens into the vagina (atresia 
vaginalis), the bladder (a. vesicalis), (1) or the urethra (a. urethralis), so 
that a real cloaca is at the same time formed. 

2d. Diminution in diameter. This anomaly exists in several de- 
grees ; in the greatest degree it constitutes imperforation (a. vera). It 
is always attended with the absence of a part, since on account of this 
defect, the part existing terminates in a cul-de-sac. 

It occurs principally in the anus, where it varies much in degree. 
Sometimes the opening of the rectum is closed only by a thin mem- 
brane, sometimes this intestine is replaced entirely by cellular tissue, o» 
by a full and solid cord. 

Next comes the large intestine, which is imperforate at a greater 
or less distance above the anus. The ileon and colon more rarely ter- 
minate in a cul de-sac. 

Still more rarely, the same exists in the small intestine, either in some 
part of its course, or at its upper extremity, or occurs in the stomach, 
preventing a communication with the small intestine, or finally exists 
in several points of the intestinal canal. 

Strictures(2) (a. spuria) are most frequent in the rectum and anus. 
They seem, however, not to be rare in the stomach, where they present 
remarkable peculiarities. In this case the stomach is most generally 
divided by a contraction near its centre, into two sacs, a right, nar- 
rower and more elongated — a left, larger and more rounded. The upper 
part of the left sac is usually not concave, but very convex, and the 
form of the two curves, particularly the inferior, are very much en- 
larged, the second presenting a deep groove. The esophagus is al- 
ways inserted at the usual place, and the cul-de-sac is never enlarged. 
The degree of contraction varies much, from half an inch to five inches, 
judging from the five cases now before us ; but the right half of the 
viscus preserves its normal direction. However, in one case we saw it 
turned on its axis, so that the convexity looked upward and forward, 

(1) Cavenne, Observation d'une imperforation de I' anus, avec ouverture de Vintestin 
dans la vessie ; in the Archiv. genir. de mid., vol. v. p. 63. — J. G. Hasselmann, De 
ani intestinirumque atresia, Utrecht, 1819. 

(2) Boyer, Rcmarques et observations sur quelques maladies de I'anus, in Journ. 
compl. des sc.mid., vol. ii. p. 24.— G. White, Observations on strictures of the rectum, 
Bath, 1820. 



288 DESCRIPTIVE ANATOMY. 

and the concavity downward and backward, and descended here before 
the right end of cardiac half. 

More rarely thc'stomach is divided by a second contraction into three 
sacs, of which the third undoubtedly arises from an unusual separation 
of the cavity of the pylorus from the rest of the cavity of the organ. 

All these anomalies are curious, as analogous with animals. They 
occur principally in females. 

When they exist, the texture of the stomach is unaltered in the con- 
tracted portion. This circumstance, however, is not sufficient to justify 
the opinion mentioned at the commencement of the paragraph, that 
this state constitutes a primitive deviation of formation, and farther, be- 
cause, as we have already mentioned, the stomach contracts transiently 
at the same place during digestion, and causes of different kinds might 
render permanent an arrangement which should be transitory. The 
greater frequency of this anomaly in females, is equally favorable to the 
two opinions. We then have reason to think that the contraction in 
question does not alwaj's occur in the same manner, and this conjec- 
ture is rendered still more probable, as it is sometimes congenital, and 
attended with other deviations of formation, which mark an arrest 
of developmental ) 

Not unfrequently, from a primitive deviation of formation, the sto- 
mach is no larger than the intestine, in which case it cannot be di- 
lated. 

We might probably mention here a valvular contraction of the left 
orifice of the stomach, which is very curiously attended with the ab- 
sence of the pyloric valve.(2) If, however, this anomaly was not con- 
fined to a simple contraction, we ought rather to refer it to the devia- 
tions of formation dependent on an excess of the formative power. 

3d. Shortness. Occurring sometimes in the whole of the intestinal 
canal, but most frequently in the vermiform appendix of the ccecum 
only. 

II. SPECIAL DEVIATIONS. 

§ 219.4. The special deviations of primitive formation are : 
1st. In the stomach. 

a. The absence of the base, which we have once observed in a 
child two months old, where the cul-de-sac of the pylorus was much 
larger than that of the cardia, which was hardly visible. 

b. Its perpendicular situation, which does not always depend on the 
abnormal enlargement of the liver, or on any other mechanical cause. 

2d. In the intestinal canal. 

a. The prolapsus of this canal into the umbilical sheath in a case of 
exomphalos. Instances of this anomaly are most frequent in the small 

(1) Sandifort, Obs. anat.path., vol. iii. p. 11. 

(2) Fleischmann, Lcichcnofnuvgcn,p. 100. 



OF THE DIGESTIVE SYSTEM. 289 

intestine, as when the development is normal, this portion of the canal 
enters last into the abdomen. 

b. The more or less perfect continuance of its primitive connection 
with the umbilical vesicle.(l) 

This anomaly exists in several different degrees. 

Sometimes the umbilical vesicle continues beyond the usual time, 
and communicates with the ileon by an open canal which the ompha- 
lo-mesenteric vessels(2) attend. 

Sometimes only a canal exists ; it varies in length, and extends 
from the same point of the ileon to the umbilicus, where it opens, and 
the omphalo-mesenteric vessels also accompany it. (3) 

Finally, sometimes a greater or less prominence exists in this place, 
a prolongation termed the diverticulum of the ileon, this is often ac- 
companied by the omphalo-mesenteric vessels, which float loosely at 
its extremity, or which are attached to the umbilicus or to another re- 
gion of the intestinal canal, so as to form a plexus. 

These three anomalies are only different degrees of the same devia- 
tion of formation. This is proved by their appearing always in the 
same place, by their connections with the omphalo-mesenteric vessels, 
and finally, the insensible shades which each presents in respect to 
length and size. 

That they have the signification we attribute to them, is proved : 
1st, by our history of the development of the intestinal canal, by their 
constant co-existence with the ccecum and vermiform appendix, and 
finally, by the fact, that they always have the character of a primitive 
formation. 

That they depend on a primitive formation, is proved by the facts, 
that they are always observed in the same place, that they are formed 
by all the membranes of the intestinal canal, and that they exist simul- 
taneously with other primitive deviations of formation, which arise 
from the development being arrested, or which, at least, favor their pro- 
ductions. 

All these circumstances united, demonstrate that it is impossible to re- 
gard them purely as accidental productions, (4) and consider them as 
excrescences,(5) or as contractions, (6) or hemias(7) of the ileon. 

In fact, the following arguments have been opposed to our theory of 
the diverticula of the ileon. 

(1) Meckel. Bcytrcige zur vergleichenden Anatomic, vol. i., pt. i., 1808. — Id., Ueber 
die Divertikel ; in Rcil, Archivfiir die Physiologie, vol. ix. part iii. — Id., Handbuch 
der ■pathologischen Anatomic, vol. i. p. 553-597. — Fulling-, Diss, de diverticula inles- 
tinali sex mensium embryonis herniam umbilicalcm referente, Marburg - , 1807. — 
Regnault, Observation d'un cas singulicr dc volvulus ; in the Journ. univ. des sc. 
Med., vol. ii. p. 108. — P. Rayer, Cas morlcld'enldrite ct de pdritonilc, ddtcrmind par 
un divcrticulc dc I'ileon ; in the Archiv. gin. dc mid., vol. v. p. 68. 

(2) Tiedemann, Anatomic der hopfioscn Missgeburten, p. 66. tab. iv. 

(3) Meckel, in Reil, loc. cit., vol. ix. 

(4) Oken, in Jcnaer Ldtcraturzeilung, 1815, no. 35. 

(5) Fleischmann, loc. cit. 

(6) Littre, Mery, in Mem. de Parvs, 1700-1701. 

(7) Fabricius and Morgagni, in Morgagni, Ep. an, mdd. 34, a. 17. 



290 DESCRIPTIVE ANATOMY. 

o. Their inconstancy,(l) their variety,(2) while all the transitory 
formations do not entirely disappear when the development is regular, 
and also the vitelline canal in birds always continues. 

b. The existence of several diverticula in the same intestine, or at 
least that of real diverticula in parts of the intestinal canal beside the 
ileon.(3) 

c. Their frequent coexistence with deviations of formation by 
doubling or arrest of development. (4) 

d. The great size and thickness of their parietes, which even did a 
canal of the umbilical vesicle exist in the early periods of life, would 
indicate an excess in the formative power. (5) 

But we have already opposed most of these objections before they 
were brought forward, and it is easy to refute them. 

The first proves nothing, for several other deviations of formation, 
which consist essentially in the development being arrested, are still 
more rare than the diverticula, and disappear entirely when the deve- 
lopment is regular. We shall mention, for instance, the permanence 
of the pupillary membrane, the absence of the extremities, the continu- 
ance of the arterial canal, the urachus, and the omphalo-mesenteric 
vessels, the fissure of the uterus. The analogy with birds, which has 
been adduced, is valueless, since even in several birds, as those of prey, 
the vitelline canal always seems to disappear entirely, and we com- 
monly observe traces of the primitive state longer in the lower animals 
than in the higher classes. 

Against the second objection, the extreme rarity of the anomaly on 
which it is founded, may be adduced. Farther, we may ask, if among 
these extremely rare cases, there are not some false diverticula ; if in 
others, the diverticulum is not produced by distension ; if in others, it 
does not depend on the union of the intestinal canal with the um- 
bilical vesicle at an unusual place ; finally, if the deviation of formation 
cannot be developed as a primitive anomaly, differently from that which 
commonly occurs, although it is impossible to conclude any thing 
from it against this latter. 

The third objection favors our views, and is opposed to the theory it 
is adduced to support ; since even where the whole body is double, some 
organs alone very rarely present the same tendency, for instance, a 
supernumerary finger or eye is not common in this case ; while, on the 
contrary, the imperfect formations, especially those depending on sus- 
pended development, as the fissure of the vertebral column, the skull, 
the palate, and the abdomen, the deviations in the formation of the 
heart and the intestinal canal by defect, are then very common phe- 
nomena. 



(2) 



Oken, in Jeancer Litcraturzeitung, 1815, no. 26. 

Emmert, Reflexions sur la vesicule ombilkalc ; in the Jaurn. compl. des sc. 
mid. vol. ii. p. 369. 

(3) Emmert, loc. cit. 

(4) Id., ib. 

(5) Id., ib. 



OP THE DIGESTIVE SYSTEM. 291 

The fourth objection is not more valid than the other three, since the 
difference between the thickness of the parietes and the size of the 
cavity of the diverticulum, depend on the period when the development 
is suspended, or on other accidental circumstances, which exert their 
influence afterward. The oval foramen is no less an anomaly, whether 
it is an inch or a line in diameter, and accidental mechanical influences 
may sometimes enlarge it during life. 

c. The great size of the vermiform appendix, depending on its con- 
tinuing to increase after the type of the fetus, although this anomaly 
may be developed at a later period. 

§ 2195. The deviations of formation, which essentially consist in an 
excess of ihe formative power, are much more rare than those we have 
mentioned. 

We should probably consider as such the division of the duodenum 
into two canals, the existence of two vermiform appendices, doubtless, 
also th© unusual length of the intestinal canal, instances of which are 
seen particularly in the large intestine, and which render it more or 
less tortuous, and especially render the transverse colon pendant. (1) 
Perhaps we must also refer to this class the real diverticula which oc- 
cur in other unusual points, although we have every reason to think 
that they should be considered as belonging to those deviations of for- 
mation relating to the quality. 

§2196. The primitive deviations of formation which concern the 
quality, relate to the form or situation, or to both. Among the latter, 
we must arrange the lateral inversions of the stomach and intestinal 
canal, since in this case, the parts are not only situated opposite their 
usual place, but also present a figure the inverse of that they normally 
possess. 

The form of the stomach or the intestinal canal, rarely presents pri- 
mitive deviations of formation in respect to quantity ; and the examples 
known of them may all be referred to anomalies in the diameter. 

The situation of the stomach is sometimes changed, this viscus being 
turned on itself so that its convex edge looks upward, and its concave 
edge downward. (2) 

B. ACCIDENTAL DEVIATIONS OF FORMATION. 

§ 2197. The accidental or consecutive deviations of formation relate 
to the extent, the mass, the situation, or the form. 

1st. Extent. 

«. Excess in extent rarely occurs in the whole abdominal portion of 
the alimentary canal, but it is observed in all its parts, and it is produced 
by very different causes, that is, particularly by obliteration, contrac- 

(1 ) P. Monterossi has figured a great many cases of this kind at the end of a memoir 
on the unusual curves of the large intestine, considered as the cause of death in new 
horn children, in Brera, Nuovi commentari di medicina, 1819, vol. iv. p. 3. 

(2) Fleischmann, toe. cit., p. 98. 



292 DESCRIPTIVE ANATOMY. 

tion, atonia, the latter always from an accumulation of substances 
within it.(l) 

The abnormal distension of the vessels of the alimentary canal, 
which not unfrequently exists, deserves to be mentioned here. It is 
most generally observed in the rectum, in the form of rounded tumors, 
which project into the cavity of the intestines, and are termed hamor- 
rhoids.{2) It is generally admitted that these tumors are situated in 
the hemorrhoidal veins ; doubtless also, the arteries contribute to them, 
although we cannot admit with Cruveilhicr, that they are new forma- 
tions, an accidental development of the erectile tissue. More probably, 
they depend in some cases on the dilatation of the small vessels, and 
in others, on that of the larger vessels, and in the last case, where they 
appear as sacs, the dilated portion is separated from the rest of the 
vessel. 

The vessels of the stomach are generally dilated in melena, and the 
black substance vomited, or which is found in the stomach, is blood 
more or less changed, which has transuded through their extremities. 

b. Abnormal contractions, when not primitive, are rarely confined 
to a simple deviation of formation. They generally succeed alterations 
of texture, inflammation, and its consequences, effusion, scirrhus, &c. 
The first commonly occurs when the alimentary canal is not distended 
by the causes which habitually act upon it, consequently after long 
fasts. 

The whole canal is affected. A contraction occurs also in a por- 
tion of this canal situated below a solution of continuity which entirely 
divided it, consequently when an artificial anus is formed after a wound 
or strangulated hernia. 

2d. We more seldom find an increase or diminution in mass without 
an alteration of texture; the first occurs particularly in the muscular 
tunic, and supervenes when this membrane has been unusually exer- 
cised. Thus it is more rare to find the stomach dilated than very 
muscular in gluttons. The muscular membrane is similarly changed 
in a herniary portion of intestine. 

The muscular tunic becomes much thinner in a general loss of 
flesh. 

3d. Situation. Deviations in situation should be referred to the 
chapter on hernias, since they generally occur in these affections. The 
small intestine is particularly liable to a change in its situation, on 
account of its greater mobility, its smaller size, and its situation. Next 
comes the stomach, which generally emerges through the linea alba 
or the upper part of the abdominal muscles, sometimes, however, 
through the umbilical ring. When abnormal openings exist in the 

(1) Chaussier, Observation suivie dc reflexions sur une dilatation excessive dc 
Vestomac ; in the Bulletin de la sac. mod. d'tnivl., 1823, September, p. 505. 

(2) Montegre, Des hemorrhoides, or Trade analytique dc ioutes les affections 
hemorrhoidales, Paris, 1819.— E. Summe, Dins, dc hccmorrlwidibus cccis, Berlin, 
1820. 

(3) Anat. pathol., vol. ii. p. 145. 



OF lilt DIGESTIVE SYSTEM. 



233 



diaphragm, they allow the stomach to pass into the cavity of the 
thorax. 

4th. The principal" changes in form are : 

a. Inversion, in which one portion of the intestine is turned, so that 
its inner face becomes the external, and the outer face the internal. 
When this change occurs at the lower part of the rectum, it is termed 
a prolapsus ani. In every other part it is called intussusception or in- 
vagination, because the inverted part enters that below it. The first 
state is more simple, since the portion of intestine which forms the pro- 
lapsus is composed of two parts, situated one on the other, the external 
of which is reversed and the infernal is normal, while in the second 
case is added a third, that into which the inverted portion enters. 
Sometimes we find a still greater number of superimposed layers, 
there being two invaginations, one within the other. 

Several invaginations often occur at the same time. 

They are most frequently situated in the small intestine, undoubt 
edly because it is the most movable portion of the alimentary canal. 

Even those intussusceptions which commence very high may de- 
• scend into the rectum and emerge from the anus. 

The most common cause of this state is the irregular action of the 
muscular membrane. Sometimes, however, it is caused mechanically 
by tumors, which force a portion of the intestinal canal downward and 

inward. 

Slight invaginations are doubtless not dangerous, and disappear of 
themselves ; but when they exist to a greater extent they cause in- 
flammation and gangrene of the herniary portion, which is usually, 
but not always, attended with death ; sometimes, however, the gan- 
grenous portion sloughs off, and the space is filled by adhesive inflam- 

5th Solutions of continuity result either from mechanical influence, 
as the action of a cuttting instrument, a rupture, or from a previous 
alteration of texture, as from ulcerations. They are sometimes com- 
plete and then affect all the tunics, sometimes confined only to the 
muscular and peritoneal membranes, whence results a hernia of the 
inner membrane, and the formation of a rounded tumor termed a jalsc 
diverticulum {d. spurium). The false differs from the true diverticu- 
lum by its rounded form, by the absence of several supenmi>osed tunics, 
and finally by its occurring in every part, even in the stomach but 
most frequently m the duodenum, and by the existence of several at 
once.(l) 

II ALTERATIONS OF TEXTUUE. 

§ 219S We not unfrequently observe an alteration m the texture o-i 
the intestinal canal, particularly in Hie stomach, which is Us sojtentng 

(1) We have enlarged upon this aubj'cct in our Jl.nd'n'ck der valhologischc* 
Anatomic, vol. ii., p. 11. 

Voi. Ill 3y 



294 DESCRIPTIVE AJNATOMY. 

or thinness, and whet) occurring in a still "greater extent its perfora- 
tion (I) This alteration is seen particularly in the large cul-de-sac 
and in the posterior wall of the stomach, and commences by the inner 
membrane, which always appears very red in this place. The edges 
of the perforation are very irregular, and differ from those of a perfora- 
tion caused by an ulcer by the total absence of thickening and hard- 
ness of the edges, which are, on the contrary, very thin and soft. 
Sometimes this change supervenes after death ; sometimes it occurs 
during life, but in both cases it is caused by the action of the gastric 
juice on the stomach, and we may consider it as resulting from the 
digestion of the membranes of the stomach by this juice, which effect 
results when the perforation occurs during life (rem some change in the 
chemical composition of the gastric fluid. (2) 

(1) Chausaier has given a good description of perforations of the stomach; we shall 
quote his words. Ulcerations and perforations of the stomach vary in form, situation, 
and extent. They.are small and circular, or large enough to introduce the hanoi 
into them. They may occur in any part of the stomach, but arc seen particularly 
at the base of this organ, in the portion corresponding to the spleen and diaphragm. 
Sometimes then the food enters into the abdomen, or the thorax if the diaphragm be 
perforated. But most generally there is no effusion, the ulcerated portion of the 
stomach being connected with the adjacent parts. If we destroy these adhesions, 
which are slight, a viscous, and sometimes a fluid, flows from the stomach, which is 
not fetid, and sometimes has an odor like musk ; it is always brownish, and mixed 
with blackish flacculre or molecules, as if finely pulverized charcoal was strewed in 
mucous serum. The edges are soft, broken, and sometimes surrounded with a more 
or less marked blackish line. In every other part the stomach preserves its usual 
form and consistence. It no where presents marks of engorgement or inflammation : 
only the capillary plexuses of its follicular membrane seem to be more developed, 
especially around the perforation. Sometimes these changes form suddenly in a 
few hours in healthy persons ; most generally, however, after several days of sickness, 
and when no violent external cause or poisoning can be suspected (Bulletin des 
sciences midicales du departement dc VEure, no. 53. p. 7). Consult also on this sub 
ject which relates to one of the most important questions in legal medicine : Gerard, 
Des perforations spontanees de Vestomac, Paris, an. xii. — Morin,. Considerations 
generates sur V6rosion, Paris, 1806. — G. Laisne, Considerations inidico-ligalcs sur 
les trosions et perforations spontanees de Vestomac; in the journal called Medecine 
Ugale, Paris, 1819, p. 135. — J. Cloquet, Sur les perforations intcstinales ; in the 
Souveau journal de midecinc, vol. i. p. 107. — Serres, Observation d'une perforation 
de Vcesophage ; in the Revue medicate, vol. x. p. 166. — Id., Observations de perfora- 
tions intestinalcs ; same journal, vol. x. p. 170. — E. Legallois, Plusieurs perforations 
du canal intestinal el specialemcnt des gros intcstins, a fa suite d'une affection tvber- 
culeuse; in the Arehiv. gen r de mid., vol. vi. p. 68. — Louis, Du rdmollissement avec 
amincissement et de la destruction dc la membrane muqueusc de Vestomac ; same 
journal, vol. v. p. 5.— Abcrcrombic, Observations sur Vinftammalion et Vnlctratfion 
de Vestomac ; same journal, vol. v. p. 447. — Louis, Observations'/datives aux perfo- 
rations spontanees dc Vintestingrclc, dans les maladies, aigues ; same journal, vol. i. 
p. 17. — U. Coste, Observations sur ics perforations de Vestomac ; in the Journ. univ. 
des. sc. tned., vol. xxix. p. 257. F. T. 

(2) This is the opinion of Hunter. We cannot admit it. It rests on Hunter's 
opinion in accordance with that of Spallanzani, in respect to the gastric juice. But 
it is very evident that the gastric juice does not exist, as these two physiologists have 
supposed, that it does not accumulate in the stomach between meals, that it is se- 
creted only at the moment when the viscus is filled with food, that this secretion is 
caused by the impression produced by the latter, and so far from being identical, it 
always varies according to the nature of the substances from which the chyme in 
found. Besides, perforation of the stomach has never been observed, in the cases of 
death by starvation hitherto observed, and that cited by Hunter should be referred 



OF TflF. DIGESTIVE SYSTEM. 295 

When the stomach is thus destroyed in one part, the softening pro- 
duced by the effused fluid extends -also to (he adjacent portions.(l) 

§ 2199. The alimentary canal frequently inflames,(2) especially in 
its mucous membrane. 

In regard to the inflammation of the stomach, we ought to remark 
that the inner membrane of this viscus, which is the most subject to 
inflammation on account of the numerous vessels it receives, the forma- 
tive power it possesses, its connections with the skin, and the direct 
effect of deleterious substances upon it, often presents, when not in- 
flamed, a very deep red color, which depends on an accumulation of 
blobd in the small twigs of the veins, and is observed particularly after 
death, from those causes which favor the stagnation of blood in these 
vessels by opposing its return to the heart. 

In inflammation of the mucous membrane, the mucus becomes 
thicker and firmer. At Ihe Same time the fibrin is effused on the inner 
face and in the substance of this membrane. The result of the first of 
these phenomena is, the formation of more or less thick, hollow, or solid 
cylinders, which pass off from the anus, and which have been wrongly 
considered as the membranes of the intestine. The effect of the se- 
cond is, to thicken the parietes, and thus to contract the cavity of the 
canal. In. the latter case partial adhesions sometimes, but rarely, 
nccur, and probably arise from ulcerations. (3) 

In ulcers of the mucous membrane, the edges are usually lightlj' 
turned over, uneven, and hard ; sometimes also their edges are smooth, 
and, as it were, cut. 

Inflammation and suppuration frequently form fistula of the anus 
(fistula a«t), that is, a canal which commences on the inner face of 
the rectum, descends on its sides, and terminates near the anus. Like 
all fistulous passages, this canal is covered internally by an cpidennis, 
similar to the mucous membranes, and is surrounded with a dense cel- 
lular tissue. (4) 

In dysentery, where the inflammation is situated principally in the 
mucous membrane of the large intestine, especially of the rectum, this 
membrane frequently mortifies in several parts, and black and dry 
eschars are formed on its surface. 



to the erosions mentioned in tlic preceding note. Consult on this subject F. G. 
Gcedecke, Dc dissolulionc veniriculi, sive de digcslione quam dicunt ventrictdi post 
mortem, Berlin, 1823. F. T. 

(1) Yelloly, Observations on the vascular appearance in the human stomach, which 
is frequently mistaken fur inflammation of that organ; in the Med. chir. trans., vol. 
iv. p. 374-125. 

(2) Scoutetten, Recherches d'anatomie palhologique, dimonstrant le rapport qui 
existe entre t' irritation dc la membrane muqutusc du canal intestinal et celle de la 
miningine ; in the Journ. univ. des sc. med., vol. xxviii., p. 257. 

(3) Monro, Morb. anat.. tab. vii. 

(1) •'• Howship, Practical observations on the most common diseases of IheVower 
intestines and anus, London, 1820. — C. Bell, A treatise on the diseases of the urethra, 
resica urinaria, prostata, and rectum, London, 1820.— T. Copcland, Observations oti 
Ihc principal diseases of the rectum and anus, London, 1814. 



'J')6 D] B( RIP i i\ i; A N \ I (> M V 

All these phenomena are usually confined to the mucous membrane. 
The tubercular formation, however, in which rounded, whitish, and 

hard masses are formed, extends from this membrane to the outer face 
of the organ, where it forms more or less evident prominences. This 
change is commonly observed in the hitter period of tuberculous phthisis, 
especially in the small intestine. The ulcerations thus affect all the 
membranes of the stomach, and then gradually extend from within 
outward. They do not necessarily result in the effusion into the ab- 
domen of substances contained in the organ ; this is even propor- 
tionally rare on account of the adhesions with the adjacent parts, or 
because the opening communicates with another portion of the intes- 
tinal canal, or with the exterior, when the wall of the abdomen ad- 
heres to the diseased organ. 

Inflammation of the peritoneal coat of thealimentary canal is often 
followed by more or less general and intimate adhesions between the 
different parts of the passage. These adhesions are sometimes so nu- 
merous and intimate that the folds of the intestines form one mass, 
which cannot be separated from the surrounding substance, and repre- 
sents only a canal hollowed in an amorphous mass. 

One of the most common alterations of texture in the intestinal canal 
is the scirrhous formation, which extends from the vascular tunic and 
the muciparous glands^ where it is primitively situated, to the mucous 
and muscular membranes. It blends together all these tunics, and 
renders them thicker and harder ; they finally present a carcinomatous 
ulceration.(l) This alteration of structure causes a contraction of the 
canal, which is often very great. It is observed more particularly in 
the pylorus, the end of the descending colon, and the rectum, which 
depends perhaps only on the disposition of these parts to retain for a 
longer period the substances which pass through them, and are also 
more exposed to irritation and its consequences. But the morbid af- 
fection extends also a greater or less distance to its primitive source, 
so that it sometimes attacks the whole stomach and a very great por- 
tion of the intestinal canal. 

Very probably we must arrange here the morbid alterations de- 
scribed by Monro, in which albumen is deposited in the vascular tunic 
for all its essential characters arc the same, and it differs from cancer 
only in its form, since it appears as small rounded bodies. (2) 

The fungous excrescences of the mucous membrane are much more 
rare. They have however been found in every part of the intestinal 
canal. Thus authors have described some cases of very large polypi 
of the stomach, one of which extepded from the cardiac orifice even 
within the duodenum. (3) We have lately found in the cadaver of a 

(1) Bourdon, Observations sur quelques maladies de f'estomac; in the Rente me- 
dicate, May, 1824. 

(2) Morbid, annt., p. 17. 

(3) Kreschot, Tumeur polypeuse eteveUppie dans, Vestomae; in (lie Bnll.de la 
fac. de mid., vol. v., 1S17, p. 37G. Other cases of this kind may be found in Monro 

Morbid anat. t tab. vi.— Fabre. Gazelle de mute, June, 1815. 



OF THE DIGESTIVE SYSTEM. 297 

young man frequently affected with abdominal affections, and who 
died of violent enteritis, two excrescences of the mucous membrane of 
the small intestine, one of which was about four lines in diameter, and 
was covered in all parts by the mucous membrane, while the other, 
about an inch in diameter, had destroyed this membrane, and was 
unattached. These excrescences are more common in the rectum(l) 
than in any other part. They are similar only in form, for they differ 
much in respect to texture ; since they are sometimes very hard and 
solid, sometimes spungy, and of a loose and soft tissue. The first pro- 
bably belong to the class of fibro cartilages, and the others to that of 
fungus hematodes. 

A tumor of the internal membrane, described by Monro as a milt- 
like tumor, and which affects the stomach particularly, is doubtless a 
fungus hematodes. (2) 

In fact, in examining the viscera of individuals who have died from a 
severe attack of small-pox, we have found the inner membrane of the 
intestinal canal very red, but have never seen in it pustules. 

The normal tissues are rarely formed abnormally in the intestinal 
canal. We must however mention here, the fatty tumors developed 
on the inner face of the mucous membrane, (3) the hairs which are 
found sometimes alone on the inner face of the inteslinc,(4) sometimes 
attended with teeth, in the stomach, (5) the ossifications of the inner 
face of the intestine,(6) and finally, at least in certain cases, hemorr- 
hoids, when they are cavernous formations. 

§ 2200. Foreign bodies of different kinds are common in the abdo- 
minal portion of the alimentary canal, particularly in the intestine. 

Those seen most frequently are the intestinal worms, which in fact 
are more common here than in any other part of. the body. The as- 
caris lumbricoides, the tcenia lata, s. bothryocephalus latus, and the 
toenia solium, live principally in the small intestine, the trichocephalus 
dispar in the large intestine, and particularly in the ccecum, finally the 
ascaris vermicularis, oxyuris vermicularis, Bremser, in the large intes- 
tine, and particularly in the rectum. 

These worms exist in the stomach only accidentally, and generally 
even not till after death. The openings through which they some- 
times pass into the peritoneal cavity are not formed by them. 

Other foreign bodies, which arc much more rare, are concretions 
introduced accidentally into the intestinal canal. They are most com- 

(1) Meckel, Handbuch dcr palhologischcn Anatomic, vol. ii., pt. ii., p. 511. — Lara- 
cine, Observation sur une tumcurfongueuse pcdiculCc dans Ic rectum ; in the Bull, 
de la soc. mid. d'imul., September, 1821. 

(2) Morbid anatomy, p. 160.— Kullier, Sur I c cancer dc I'cstomac; in the Archiv. 
gin. dc mid., vol. ii., p. 380. 

(3) Meckel, Handbuch dcr pathologifchcn Anatomic, vol. ii., pt. ii., p. 124. 

(4) Meckel, Mimoire sur les poils ct les dents qui se dcteloppent accidentcllement 
dans le corps ; in tlie Journ. compl. dessc. mid., vol. iv., p. 122, 217. 

(5) Rqysch, Advers. anat., dec. iii. 

(6) Meckel, Handbuch der pathologischcn Anatomie, vol. ii., pt. ii., p. 227. 



2i)8 DESCRIPTIVE ANATOMY. 

monly biliary calculi, which descend into it from the gall bladder. 
Next come the abdominal concretions, which form partially or wholly 
in the intestine.(l) 



ARTICLE FOURTH. 

CLANDULAR ORGANS OF THE ABDOMINAL PORTION OF THE 
DIGESTIVE SYSTEM. 

§ 2201. The glandular organs of the abdominal portion of the di- 
gestive system, (2) termed also, together with the stomach, the chylo- 
jyoietic viscera (viscera chylopoiclica), are the liver, the pancreas, and 
the spleen. They are situated in the upper half of the abdomen, and 
are intimately connected with each other, and with the stomach and 
the duodenum, not only in situation but also in the vessels and nerves 
thej' receive, but even, except, in the spleen, in continuity of substance. 
In fact they receive their vessels from the same trunk, the cceliac 
artery ; their nerves come from the same source, the solar plexus ; 
finally, the excretory canals of the liver and pancreas, which open into 
the duodenum, are in fact folds of the inner membrane of this intestine. 



A. PERFECT STATE. 

a. Situation. 

§ 2202. The liver (hepar, jccur),(3) the largest gland in the body, 
occupies all the right hypochondriac region, the upper part of the epi- 
gastric region, and in the female particularly, part of the left hypo- 
chondriac region. It descends on the right side lower than on the left, 

(1) Meckel, Rcmarqucs sur les concritions qui sc rccontrcnt dans le canal intestinal 
chex Vhommc ; in the Journ. compl. des sc. mid., vol. ii., p. 125. 

(2) J. Fantoni, Dc jecore, lienc ct pancrcate ; in the Disc, rcnov., Turin, 1745. 

(3) A. Rolfink, Dc hepatc, Jena, 1633.— F. Glisson, Anatomia hepatis, London, 
1654.— M.- Malpighi, Dc hepatc ; in the Dc viscerum struclura, Bolog-na, 1666.— J. 
B. Bianchi, Historiahcpatica, Turin, 1711.— A. Bertrandi, Dc hepatcet oculo, Turin, 
1748.— A. Frankcn, Hist, hepat. anat., Leyden, 1748.— J. G. Gunz, Obs. circa hepar, 
Leipsic, 1748.— A. Ferrein, Sur la structure des visccrcs nommes glanduleux, ct par- 
ticular cment sur celle des reins et du foie ; in the M&m. dc Pari*, 1749, p. 709.— 
M. Ambodick, Dc hepatc, Strasburer, 1775.— F. A. Walter, De slructura hepatis ct 
resicula fella; in the Annot. acad., Berlin, 1786.— Saunders, A treatise on the struc- 
ture, economy, and diseases of the liver, London, 1798.— J. M. Mappcs, Diss, dc pent- 
tiori hepatis human i struclura, Tubingen, 1817.— Id., Quelques considerations sur 

ta structure du foie ct du rein ; in the Journ. compl. des sc. mid., voL xii., p. 223. • 

J. F. BclLz, Qiuedam dc hepatis dignitate, Berlin, 1822. 



OF THE DIGESTIVE SYSTEM. 299 

so that it is situated obliquely from below upward, and from right to 
left. On the left side it terminates near the upper extremity of the 
spleen ; its left portion covers the stomach, the right generally the 
whole right kidney, but when the latter organ is situated lower than 
usual, only its greater upper half. 

B. DIMEN6IOH AND WEIGHT. 

§ 2203. The transverse diameter of the liver in the adult is usually 
from ten to twelve inches ; the anteroposterior is from six to seven 
inches. The gland is two inches high in its thickest portion. 

The liver generally weighs about four pounds in the adult, so that 
its weight in proportion to that of the whole body is as 1 : 36. 



§ 2204. The form of the liver is irregular and quadrangular. It is 
much thicker from one side to the other than from before backward, 
and is thinnest from above downward. 

§ 2205. The liver is generally divided into two halves or lobes (loin), 
the right and the left, separated on the upper face by the suspensory 
ligament, on the anterior edge by a deep groove, and on the lower face 
by a deep longitudinal fissure, which extends the whole breadth of the 
gland. 

§ 2206. The right lobe (I. hepalis dexter, s. major) is about four 
times as large as the left (I hepatis sinister, s. minor), and much ex- 
ceeds it in all its dimensions, but particularly in its thickness. 

Its upper face is uniformly convex ; the lower presents elevations 
and depressions which render it very uneven. 

These inequalities are connected with the blood vessels, the lym- 
phatics and the biliary vessels which enter or emerge from the liver, 
and correspond to the fissures (hilus) of the other glandular organs. 

The two edges of the liver, the anterior or inferior, and the posterior 
or superior, are generally convex, but the first is more so than the 
other. The anterior is thin and sharp, the posterior thick and blunt, 
so that the upper and lower faces gradually unite in that part, al- 
though there is a very distinct limit between them. 

The left portion of the lower face of the right lobe, which is the 
smallest, and which occupies the centre of the lower face of the liver, 
considered as a whole, has the form of an H inclined from before back- 
ward, the transverse bar and the two legs of which are formed by the 
fissures (sulci, s. fovea) which converge behind the lower face of the 
'liver, between which are the elevations (lobuli). 

§2207. The transverse or median fissure (sulcus intermedins, s. 
transversus) is situated about the centre, a little nearer the posterior 
than the anterior edge. We notice in it the commencement of the 



300 " DESCRIPTIVE ANATOMY 

excretory duct of the liver, or the hepatic canal (d. Inpatient), the com- 
mencement of the arterial portion of the vena-porta and the hepatic 
arteries. The hepatic canal is situated entirely forward, the vena- 
portce between an anterior and a posterior series of branches of the 
hepatic artery. Each of these three vessels divides into a right and a 
left branch ; from the hepatic artery are commonly formed two, which 
are entirely distinct, a right and a left. 

§ 2208. The left longitudinal fissure (fossa longiludinalis sinistra), 
which separates the right from the left lobe, extends from the anterior 
to the posterior edge. The left extremity of the vena porta; divides 
these into two halves, an anterior, longer and deeper, and a posterior, 
smaller and more superficial. 

The anterior half (fovea pro vena umbilicali, s. lig. terete) is the 
groove for the umbilical vein or the round ligament of the liver. 

Gunz has asserted, contrary to most anatomists, that this anterior 
half is most generally changed into a real canal, as in almost all ani- 
mals, by one or more bands of the substance of the liver, which extend 
like a bridge from the lower face of the great lobe to that of the small, 
and are sometimes also replaced by a simple prolongation of the peri- 
toneal capsule of the gland. 

The posterior half of the left longitudinal fissure, which is more su- 
perficial than the anterior, especially toward the left lobe, is the fossa 
for the venous canal (fossa pro ductu venoso), which is there directed 
from before backward, from below upward, and near its termination a 
little from left to right. 

It is continuous posteriorly with the fissure of the ascending vena- 
cava. 

We rarely find it intimately united with the venous canal by a 
layer of the substance of the liver, which is then very thin. 

§ 2209. The right longitudinal fissure (fossa longitudinalis dextra) 
is much more superficial, and its anterior part, separated from the pos- 
terior by the vena-porta, differs much from this latter in form and in 
importance. 

The anterior is planer and is not covered by the peritoneum ; it re- 
ceives the gall bladder (fossa pro vesiculd felled). This depression is 
most generally indicated forward by a greater or a less groove, and 
sometimes it communicates near its anterior extremity with the upper 
face of the liver by an opening. 

The posterior is directed from below upward, and is continuous with 
the posterior edge ; it is termed the fossa of the vena-cava (fossa vciuc 
cavm), because it receives the upper part of the ascending vena-cava. 
It blends posteriorly in the blunt edge of the liver with the fissure of 
the venous canal. It is rarely wholly or partially changed into a canal 
by a band of the substance of the liver. 

About twenty small hepatic veins proceed from this fossa from below 
upward, in pairs side by side, and empty into the ascending vena-cava ; 
but from its upper part arise two large venous trunks, a right and a 
left, which terminate in the dame manner. 



OF THE DIGESTIVE SYSTEM. 301 

Thus the vena-cava follows, in the arrangement of its branches, the 
same law as the other vessels of the liver, and although the latter is a 
simple organ, it seems composed of two halves, a right and a left. 

Its vascular fissures are separated from each other on the lower 
face by the posterior middle lobe ; they however blend together pos- 
teriorly. 

§ 2210. The portion of the lower face of the liver, situated between 
the two longitudinal fissures, is divided by the portal eminence into two 
halves, an anterior and a posterior. 

The anterior, which is deeper, is situated between the depressions 
of the gall-bladder and the umbilical vein on one side, and the portal 
eminence and the anterior edge on the other, and has been called from 
its form the square lobe (I. quadratus). 

The posterior is smaller, more elongated, narrower, but more promi- 
nent, because situated on a narrower base, is found between the porta, 
the fissure of the ascending vena-cava, that of the venous canal, and 
the posterior edge. It is termed the lobe of Spigel (lobulus Spigelii t 
s. caudatus). 

§ 2211. The right portion of the lower face of the great lobe is the 
most extensive and thickest, and is uniformly convex or concave. 

§ 2212. The left lobe, which is much smaller and thinner, gra- 
dually terminates in a blunt extremity. Its upper and its lower faces 
are smooth and united. 

Beside the fissures we have described, we not unfrequently find, 
particularly in the right lobe, several which vary in size and are not 
constant ; these are analogous to the division of the liver into many 
lobes in the mammalia. 

D. ATTACHMENTS. 

§ 2213. The liver is enveloped by the peritoneum, except the jight 
part of its posterior edge and the portion of its lower face covered by 
the gall-bladder. This membrane is reflected on it backward by its 
blunt edge, and forward by the portal eminence or the suspensory liga- 
ment. There is no other envelop between it and the tissue of the 
gland in most of its extent ; we however find an intermediate layer of 
cellular tissue at the posterior part of the upper face near the edge. 

§ 2214. The liver is kept in place by several folds of peritoneum, 
namely : 

1st. By the coronary ligament, at its posterior edge. 

2d. By the right and left triangular ligaments, which form its right 
and left extremities, to the lower face of the diaphragm. 

3d. By the suspensory ligament, which is attached to the lower face 
of the diaphragm and to the linea alba. 

The small epiploon unites it to the small curve of the stomach. 

A short cellular tissue also unites it very loosely to the right kidney, 
which it receives in a depression of the lower face of its right lobe. 

Vol. III. 39 



302 DESCRIPTIVE ANAT031V. 



E. COLOR, SPECIFIC GRAVITT, AND CONSISTENCE. 

§ 2215. The color of the liver is brownish red in young persons and 
those in the prime of life. It becomes darkish and blacker in old age. 
Its specific gravity is about as 15 : 10. 

Its substance is firm, but brittle. Thus the liver is one of the organs 
most frequently ruptured, from a mechanical cause acting on the pa- 
rietes of the abdomen when the external parts are uninjured. 



F. TEXTURE. 

§ 2216. The parenchyma of the liver is not absolutely homoge- 
neous. In fact we do not find, as in the other glands and the ence- 
phalon, the two substances of which it is composed separated from 
each, so that one is placed internally and the other externally. But 
whatever point we examine, these two substances, which are every 
where arranged alternately, are easily distinguished. At first view 
they seem to form undulated bands about half a line thick ; but when 
examined more attentively we perceive that the yellow forms a co- 
herent mass in all parts of the gland, that it there produces numerous 
elevations and depressions, although interrupted in many parts, and 
consequently represents a very complicated net-work. In the spaces, 
which are about a line in diameter, and which are polygons, we find 
a dark substance which does not form a coherent whole like the pre- 
ceding, and which is softer but less transparent than it. 

Ferrein had already well distinguished these two substances. (1) 
Haller(2) and Gunz(3) also mention its discovery. Autenrieth,(4) 
Bichat,(5) Cloquet,(6) and Mappes,(7) have also mentioned this struc- 
ture, which we have always thought was easily seen ; hence we con- 
sider as erroneous the opinion(8) that they are arranged arbitrarily. 
Physiologists, however, differ in regard to their uses. Ferrein terms 
the deep colored substance the medullar]}, and the bright colored sub- 
stance the cortical ; while Autenrielh and Mappes have applied these 
terms in opposite senses. The views of these last two writers seem 
to us to be more just than those of the others regarding the difference 
in the consistence and ■ the transparency of the two substances, in re- 
spect to their color, or finally their arrangement in regard to conti- 
nuity, since in all these respects the bright substance is more similar 

(T) Mim. cle Paris, 1733, hist. 51. 

(2) Bibl. anat., vol. ii., p. 253. 

(3) De hepatc, r,. 28. 

< 4 ) . Veb ,i r J i£ ™ d ™ substanz dcr Leber; in Rcil, Archir. fur die Physioloeie, 
vol. vu., 1817, p. 229-308. * ° * 

(5) Anat. descript., vol. v., p. 93. 
{6\ Traiti d'anat., vol. it., p. 1032, 1033. 

(7) Loc. cit., p. 6. 

(8) Portal, Anat. prat., 1804, vol. v., p. 278. " 



OF THE DIGESTIVE SYSTEM. 303 

to the bright substance of the encephalon, the spinal marrow, and the 
kidneys ; and the dark substance to the cortical substance of these 
latter. 

When the yellow medullary substance is examined attentively, it 
seems formed of small points or grains. 

We may term the small masses composed of medullary and of cor- 
tical substance the lobules (acini), although they are more blended 
than in the other glands, and are not separated by spaces filled only 
with cellular tissue ; so that the structure of. the liver is consequently 
much less lobular than that of the salivary glands. 

From the consistence and hardness of the substance of the liver, the 
orifices of the vessels which are intimately united with it remain ga- 
ping when it is cut. 

§ 2217. The liver is formed by the ramifications of the biliary ducts, 
of the vena-portae, of the hepatic artery and the hepatic veins, and by 
lymphatic vessels and nerves, united by mucous tissue. It is, how- 
ever, essentially formed by the biliary vessels and the mucous tissue 
which surrounds them. 

§ 2218. The vessels of the liver are not all distributed exactly in 
the same manner. They vary in their connections with each other, 
and with the substance of the organ. 

The hepatic artery, the vena-portae, and the biliary ducts are enve- 
loped in their whole course through the substance of the liver by a 
common cellular sheath, a prolongation of the capsule of Glisson. 
Hence they are not in direct contact with the substance of the gland, 
like the ramifications of the hepatic artery, around which the capsule 
does not exist, and they are more solid and more resisting than the 
latter. 

The hepatic artery seems to be intended for the nourishment prin- 
cipally of the tissue of the liver ; for according to Glisson's observa- 
tions, (1) which have since been proved correct by Bianchi,(2) Wa!- 
ter,(3) and Mappes,(4) it is distributed on the other vessels, giving rise 
there to a very complex net-work. The finest ramifications, however, 
enter the vena-portae. (5) 

Its branches are fewer and straighter than those of the latter.(G) 
When injected it is generally entirely filled, but sometimes this is true 
only of the vena-portae.(7) 

§ 2219. The vena-portce forms by far the largest part of the vascu- 
lar substance of the liver. It ramifies very frequently, and evidently 



(1) L. i., c xxix., De artericc hepatis distributione, 

(2) Loc. cit., pt. i., cap. viii., § 5. 

(3) Loc. cit., p. 96. 

(4) Loc. cit., p. 13. 

(5) Walter, p. 96, 99. 

(6) Id., p. 95, 96. 

(7) Id., p. 68. 



304 DESCRIPTIVE ANATOMY. 

like a disk, although one of the two branches is much larger than the 
other.(l) 

It terminates in two modes ; several branches, some of which are 
very large and even a line in diameter, anastomose with the corre- 
sponding twigs of the hepatic veins,(2) and hence the facility with 
which the vena-portse is injected through these latter, or the hepatic 
veins through the vena-portce.(3) Other and more minute branches 
are more particularly connected with the origins of the biliary ducts ; 
but their connections are less intimate than those we have mentioned, 
since by injecting the vena-portse we can never fill the biliary canals 
alone, but the injection always passes into the other vessels, particu- 
larly into the hepatic veins.(4) Its most minute twigs do not enter 
into the medullary substance of the liver, but are distributed in the 
cortical substance, and have no direct or proximate connection with 
the first.(5) 

§ 2220. The biliary canals differ from the other vessels of the liver, 
as their twigs are larger. Only the large branches unite in the man- 
ner of a disk. The union of the small twigs is less regular, and seve- 
ral proceed from the same point. Their parietes are much firmer than 
those of the veins. The muciparous depressions upon their inner 
face on the outer half of the liver do not • exist except in the largest 
branches, and entirely disappear in the most minute, which are per- 
fectly smooth. When they are injected the injection generally pene- 
trates into no other kind of vessel, or when this happens the lympha- 
tics,(6) and next the branches of the vena-portae are most perfectly 
and frequently filled. 

The roots of the biliary canals seem to arise on the limit between 
the medullary and the cortical substance, although they do not dis- 
tinctly pass through the former.(7) They never terminate on the sur- 
face of the liver, and even when they are superficial, they penetrate 
within the gland. 

2221. The twigs of the hepatic vein are also fewer and larger than 
those of the vena-portae and the'hepatic artery. They do not contribute 
as much as the vena-portas, to form the substance of the liver,(8) 
although their less degree of development is only apparent, since their 
twigs are so small, that they are more easily destroyed than the other 
hepatic vessels. When injected, the fluid scarcely passes, excepting 
into the vena-portae.(9) Their direction is generally transverse, while 
that of the other hepatic vessels is oblique from below upward, and 
almost perpendicular, so that they cross these latter. Their final twigs 

(1) Mappes, p. 13. 

(2) Bertin, in the Mim. dc Paris, 1765.— Walter, p. 94. 95. 

(3) Walter, p. 63.— Mappes, p. 23. 

(4) Id., p. 64, 65.— Mappes, p. 22. 

(5) Mappes, p. 11-13. 

(6) Walter, p. 70.— Mappes, p. 24. 

(7) Mappes, p. i. 

(8) Walter, toe. tit. 

(9) Glisson, p. 285. 



OF THE DIGESTIVE SYSTEM. 305 

are more intimately connected with their medullary substance than 
those of the other hepatic vessels, and it is more or less easy to trace 
them into this substance, which depends partly on their not being sur- 
rounded like these latter by the cellular capsule. 

§ 2222. The lymphatics of the liver are intimately connected with 
the biliary ducts, and their cavity directly communicates with them, or 
at least the substance between them is extremely thin, soft, and easily 
destroyed.' Those of the different regions of the liver do not anasto- 
mose together, for the injection of one branch fills only the portion of the 
organ to which this branch is distributed. 

B. EXCRETORY TORTION OF THE BILIARY SYSTEM. 

§ 2223. The excretory portion of the biliary system includes the 
proper excretory duct of the liver, and a cul-de-sac of this canal termed 
the gall-bladder (cystis, s. vesicula fellea, cholecystis) . 

A. EXCRETORY DUCT. 

§ 2224. The excretory duct, of which we have already described the 
portion within the liver, is formed by two membranes, one external, 
solid, and cellular, the other internal, thicker, and smooth presenting 
numerous and very compact depressions. We distinguish in it three 
portions, the hepatic canal, the cystic canal, and the ductus choledochus. 

The hepatic canal (d. hepaticus), or the first portion of the excretory 
duct, arises in the fissure of the vena-portaj generally by two branches, 
one on the right, which is smaller, and comes from the anterior part of 
the great lobe of the liver, the other on the left, which is larger, and 
arises from the posterior part of this lobe, and from the left lobe. These 
two branches anastomose at an acute angle before leaving the fissure 
of the vena-portae. The canal formed by their union is from one and a 
half to two inches long, and nearly two lines broad in the normal state ; 
it is directed from above downward, and from right to left, and divides 
to give rise to the cystic canal and the ductus choledochus, which 
make a part of it. 

The cystic canal (d. cysticus) is directed at an acute angle forward, 
downward, and to the right. It is narrower* and usually a little 
longer than the hepatic, and enlarges to form the gall-bladder. 

B. GALL-BLADDER. 

§ 2225. The gallbladder is situated in a special depression of the 
lower face of the liver. It is usually pear-shaped. The extremity, 
near its orifice, termed the neck (cervix), is the narrowest part ; it is 
broadest in its centre. Its anterior extremity terminates in a cul-de-sac, 
and is called the base (fundus) ; it commonly extends a little beyond 
the anterior edge of the liver. The gall-bladder generally adheres in- 



306 DESCRIPTIVE ANATOMY. 

timately by its upper part, to the lower face of the liver, but sometimes 
also it is loosely united with it by a fold of the peritoneum. The peri- 
toneum covers it more or less perfectly, according as it presents one or 
the other of these two arrangements. 

We find below the peritoneum a dense cellular tissue, in which pro- 
ceed the large vascular trunks, and which is called the vascular or ner- 
vous tunic. The external face of the second tunic presents some fibres 
which are generally whitish, proceed in different directions,- sometimes 
very analogous to those of the muscular coat of the intestinal canal, and 
which cannot be considered as forming a distinct layer. 

The cellular tunic covers the internal or mucous membrane, the in- 
ner face of which presents folds which represent a reticular tissue, 
formed of irregular pentagons, which do not disappear even when the 
gall bladder is in its greatest possible state of distension. Some very 
small openings, which are observed on this face, lead to simple glands 
which are commonly invisible. Only ramifications of veins are distri- 
buted on the surface of the folds. 

The cystic canal and the neck of the gall-bladder are contracted by 
about a dozen transverse folds, which are real valves, and arise from 
the internal and cellular tunics. Most of these folds have their loose 
edge turned toward the cavity of the gall-bladder, so as to form between 
them and the wall of the canal, a depression which has the same di- 
rection. 

These folds gradually enlarge from the hepatic canal toward the 
neck of the gall-bladder. They are attached to each other, especially 
the largest, by intermediate, longitudinal, oblique, elevations which are 
less prominent. 

§ 2226. The ductus choledochus, or the lower portion of the excre- 
tory canal of the liver, is the continuation of the hepatic and the cystic 
ducts. It is a little broader than these two canals, but it is more 
similar to the hepatic in structure and diameter, and may be con- 
sidered the direct continuation of it, for it has the same direction, and 
there exists, at least very frequently, along the opening of the cystic 
canal, a small elevation between it and these two passages. 

This canal is generally about four inches long ; its lower extremity 
goes to the posterior wall of the duodenum, and opens at its central 
portion. Its diameter is generally the same until it opens into the in- 
testine, but it contracts much in gliding between the muscular and cel- 
lular tunics of the latter, and finally terminates in an orifice which is 
narrower than the rest of its course. 

§ 2227. When we cut the duodenum, we observe in the posterior 
wall, the opening of the ductus choledochus, in the form of an oblong 
tubercle, about four lines in length, and presenting at its lower extre- 
mity an opening directed obliquely from above downward ; this open- 
ing is generally situated three' inches below the commencement of the 
intestine, and is formed by the mucous and cellular membranes of the 
latter and the ductus choledochus, which are uninterruptedlv continu- 
ous with each other. 



OF THE DIGESTIVE SYSTEM. 307 

The lower part of this orifice does not belong to the duct as chole- 
dochus alone, but it is common to the pancreatic canal. 

§ 2228. The most evident function of the liver, is the very important 
one to secrete bile, a green, very bitter alkaline liquid, which is indis- 
pensibly necessary to digestion ; its physical qualities vary much in 
more than one respect. The bile is generally distinguished into cystic 
and hepatic ; the first is thicker, darker, more bitter, and consequently 
more concentrated than the second ; which differences depend on the 
gall-bladder, and not on the different origin of these two fluids, although 
Malpighi(l) and Galeati(2) have adopted this last opinion, or at least 
in part. 

It is very probable, that putting out of view this difference of con- 
centration, the bile has not always the same chemical composition. 

It always contains a considerable quantity, and generally about 
eleven-twelfths of water. The rest is composed, according to Thenard, 
of albumen and of resin, of each about an equal quantity, which form 
almost the whole of it ; a small quantity of insoluble 3'ellow substance, 
of a still smaller quantity of soluble substance, finally, some traces of 
soda, of the phosphate, the sulphate, and the hydrochlorate of soda ; of 
the phosphate of lime, and of the oxide of iron, all of which are dis- 
solved in the water except, the yellow substance, which is insoluble. (3) 
The resin admitted by Thenard and his successors, is produced, ac- 
cording to Berzelius,(4) by the action of acids on a peculiar substance, 
similar to albumen. This chemist considers bile composed in 1000 
parts : of water 907.4 ; of a peculiar substance 80.0 ; of mucus 3.00 ; 
of soda and common salts 9.6. None of these constituent parts con- 
tain azote ; this is curious, on account of the frequent change of bile 
into a fatty body, and on account of the analogy of the meconium with 
vegetable substances. 

Thenard asserts that picromel, a peculiar substance of a sweet and 
bitter taste, which commonly occurs in the bile of most mammalia, 
does not exist in that of man, but it has been found there by Che- 
valier.(5) 

Probably the bile is formed entirely, or in great part, at the expense 
of the venous blood of the vena-portae, and the hepatic artery only 
serves to nourish the liver. 

The principal arguments in favor of this opinion, are : 
1st. The distribution of the hepatic artery in the vascular mem- 
branes. 

2d. The existence even of the system of the vena-portae. 
3d. The great analogy between the venous blood and the bile, and 
between it and the arterial blood. 



(1) De liene., c. vi. 

(2) Com. Bonon., vol. i. ib. vol. ii. p. i. 

(3) Mem. de lasoc. d'Arcucil, vol. i. 

(4) Med. ckir. trails., vol. iii. 

(5) Annates dcchimicet de physique, vol. is. 



303 DESCRIPTIVE ANATOMY. 

4th. The relation between the caliber of the hepatic vein and the 
size of the liver, without regard to the abundance of the biliary secre- 
tion, while this latter circumstance is always attended with a greater 
development of the vena-portre. 

The arguments adduced against this theory, are : 

1st. The absence of the system of the vena-ports; in the invertebral 
animals. 

2d. The cases where the vena-portse opens into the vena-cava, and 
the hepatic artery is unusually large. 

3d. The correspondence between the caliber of the excretory duct 
of the liver and that of the hepatic artery, and the disproportion be- 
tween that of the hepatic canal and that of the vena-portae. 

These arguments do not refute those on the other side. We have 
reasons for. thinking that the arterial blood of the invertebral animals 
is. perhaps more proper for the secretion of bile than that of the verte- 
brated animals. Possibly, also, the arterial blood of the latter was 
more appropriate for this use in the anomaly on which the second ar- 
gument rests, than generally, because the biliary secretion then did 
not contribute to render the blood of the vena-portal more analogous to 
that whioh circulates in the arteries. Farther, all the known cases of 
this anomaly have been observed in children, the bile being less bitter 
and less in quantity than usual. As to the third objection, the hepatic 
artery compared with the arteries of the other secretory organs, seems 
too small to admit that it serves for secretion and nutrition. 

Some physiologists, regarding the size of the liver, its constant ex- 
istence, and the frequency of its diseases, have been led to believe that 
it fulfills in the economy another function from that of secreting bile ; 
but this other function is not proved. Theuses of the bile arenot confined 
to digestion, but it is- connected with the whole vital action ; in this re- 
spect, the secretion which forms it, prevents an excess of hydrogen and 
carbon in the body, as is indicated by its increase when the respiratory 
function diminishes in the animal series, when it does not exist as in 
the fetus, or when it is deranged as in certain diseases. (1) 

The purpose of the circulation of the vena-portae, however, may also 
be to attenuate, to assimilate foreign substances brought by the venous 
system into the intestinal canal, and thus diminish the injurious in- 
fluence they might exercise on the body. 

C. DIFFERENCES DEPENDING ON DEVELOPMENT. 

2229. The differences depending on the development of the liver(2) 
relate to its volume, situation, form, and texture. 

1st. The liver is very large during the first week of gestation, and 
we may say from the first moment of its appearance, that it is propor- 

(1) Meckel, Abhandlungen, 180C. 

(2) Walter, loc. cit., sect. i. — A. Portal, Observations suria situation des visccres du 
bas-ventrc chez les enfans, et sur Ic deplacement qu'ils eprouvent dans un age plus 



OF THE DIGESTIVE SYSTEM. 309 

tionally much larger the younger tho fetus is. Thus, in the fetus of 
three weeks, its weight is one half that of the rest of the body,(l) and 
even in the full grown fetus it is to the latter as 1 : 18, or as I : 20, 
while the relation is as 1 : 35-36 in the adult. But the great propor- 
tional size of the liver diminishes at the end of the first half of gestation, 
because, after this period, the gland increases more slowly. It, how- 
ever, continues to grow till birth ; but afterward the absolute weight 
and size diminish until the end of the first year, for we have found in 
five new born children, that the liver was one quarter heavier than in 
five other children from eight to ten months old. 

2d. The liver at first occupies a much greater space the younger 
the fetus is ; even at the third or fourth month of gestation, it nearly 
fills the cavity of the abdomen, desTi?ftds to the crest of the ileum, and 
covers the other viscera. This difference, however, partly depends 
upon its being situated more perpendicularly at first, so that then, that 
face which is afterwards superior, looks forward, and that which is to 
be inferior, backward. 

3d. Its formation is at first as much more symmetrical as is its situ- 
ation, and its left lobe differs less in size from the right lobe, and the 
limit between these two parts corresponds more to the median line. 
The absolute diminution mentioned above, takes place almost entirely 
at the expense of the left lobe, for while during this period, the right 
lobe preserves the size it had at birth, and often even increases a little; 
the left diminishes in every direction, so that in a child of a year old, it 
is hardly half as large as in a new born child ; the lobe of Spigel, on 
the contrary, is more developed. The liver is at first more rounded, 
and its lower face is more convex than it is afterwards. 

4th. Its tissue is softer, more homogeneous, more brittle, and more 
vascular in the earlier periods of life than subsequently, where the ves- 
sels diminish in size, and many of them disappear. We, however, 
very readily distinguish the two substances in the full grown fetus. 

5th. Its color is at first a bright grayish brown ; it does not become a 
deep red until after the first half of gestation ; its tint, brightens shortly 
after birth, and its tissue then changes also a little in appearance. 

§ 2230. The gall-bladder is at first entirely concealed in the substance 
of the liver, is proportionally very long, narrow, filiform, a little en- 
larged at its lower extremity, and empty. Its cavity cannot be 
seen except by the aid of the microscope. Its inner membrane is 
smooth until the sixth month of gestation ; broad, irregular elevations 
are then developed in it, between which are narrow depressions, similar 
to superficial grooves. These grooves gradually become deeper, and 
also more numerous, and many fissures are developed on the surface 

avance ; in the Mtmoires de Paris, 1771.— Id., Obscrralions sur la situation dufoic 
dans Vctat nature!, arte des remarqv.es sur la maniire de connaitre, par lc tart, p/v- 
sicurs dc scs maladies ; in the M6m. de Paris, 1773. — J. vS. Schumann, Dehepatis 
inembryone magnitudinis causis ejusdcmqucjujictionc rum inja:tn turn inhumine 
nato, Breslau, 1817. 
(1) Walter, loc. <:it., p 15. 

Vol. Ill 40 



310 DESCRIPTIVE AN ATOM V 

of the elevations ; hence, regular and narrow cellules are formed, which 
are separated by thin intermediate septa. 

Notwithstanding its primitive narrowness, the gall-bladder is never 
deficient at any period, according to our observations, as one would be 
led to believe from some cases where its total absence has been assert- 
ed. Its situation also in regard to the other biliary organs, is always 
the same ; consequently it never arises by a kind of granulation, deve- 
loped from the extremity of the biliary passage, but it arises in the 
groove at the lower part of the liver, which is destined particularly for it, 
and which is at first proportionally much deeper than in the adult. 
We have never known it to communicate with the liver at first by 
one or more special canals, while wc have seen it manifestly terminate 
in a cul-de-sac. 



D. ABNORMAL STATE. 

§ 2231. The liver is one of the organs most(l) frequently abnormal 
in more than one respect, but principally in its texture, which undoubt- 
edly depends on the numerous organic elements which compose it. 



§ 2232. The deficiency of the liver has hitherto been observed only 
in some acephalous monsters ; in these it is the rule, which has but few 
exceptions, that the liver is always very small. 

This organ sometimes preserves the same situation as in the fetus, 
which depends on the imperfect development of the anterior face of the 
abdomen. In this case it is sometimes situated externally, forming 
either alone or with the other viscera, an umbilical hernia, in which it is 
wholly or but partially contained. It exists more rarely in the cavity 
of the thorax, on account of the imperfect development of the dia- 
phragm. Sometimes, in these two cases, especially the first, the her- 
niary part, forms a prolongation, which is attached to the peduncle ; 
this may give rise to the opinion that two livers exist. Sometimes, 
also, when no similar mechanical cause exists, the liver is divided by 
more or less deep grooves, into a greater or less number of distinct 
lobes. 

Sometimes an anomaly of the liver exists, similar to the latter in ex- 
ternal appearance, but differing much from it in form and origin. It 
consists in fractures of this organ, which are frequent on account of its 
fragility, even when the external parts are uninjured from external 

(1) Portal, Observations sur la nature etle traitement des maladies defoie, Paris, 
1813.— Farre, The morbid anatomy of the liver, London, 1812-1815. — J. Thomas, A 
treatise on the diseases of the liver and digestive organs, London, 1820. — J. Johnston, 
A treatise on derangement of the liver, London, 1820. — J. Faithorn, Facts and obser- 
vationson liver complaints and bilious disorders in general, Philadelphia, 1820. 



OF THE DIGESTIVE SYSTEM. 311 

causes, acting not only on the region of the body in which it is situa- 
ted, but also upon remote parts. 

It is rare that the liver is abnormally small from a primitive devia- 
tion of formation, but it often diminishes in the course of time, particu- 
larly in advanced life, and finally becomes unusually hard and firm ; 
this state is termed scirrhus, although this term is not perfectly con- 
venient. 

Hypertrophy (1) of the liver is one of its most common affections ; it 
supervenes at all periods of life, but most frequently in advanced age : 
it is generally attended with a greater or less alteiation of texture, and 
particularly with induration, even when it does not depend solely on 
new formations within the gland. 

Induration of the liver, however, is not always attended by its hy- 
pertrophy, although the contrary is generally admitted, since the latter 
is sometimes attended with softening. Hypertrophy of the liver fre- 
quently attends chronic general diseases, especially rachitis, scrofula, 
and dropsy. In this case the gland is usually harder than in health : 
but in scrofula, on the contrary, where we find hypertrophy at least as 
frequently, its tissue is softer than in the normal state. The enlarge- 
ment of the liver, which usually attends pulmonary affections, is evi- 
dently, at least in most cases, an effort of nature to restore health. 

Induration of the liver is the most frequent alteration of texture, and 
it often exists with or without enlargement. Softening of the liver is 
much more rare, and exists sometimes with, and sometimes without 
atrophy of the glan J. (2) 

The new formations in the liver are rarely repetitions of the normal 
tissues : the most common anomaly is the change into fat, which exists 
in several different degrees, usually affects the whole organ, and is ob- 
served in the idle and luxurious. 

Accidental ossification is generally developed on the edge of the 
liver, below the peritoneal coat. Probably it is only a change of 
another accidental formation, for instance, of one of those serous or 
fibroserous cysts, often developed in the liver, where they form hy- 
datids. 

The liver is not unfrequently the seat of entirely new formations, 
generally termed tubercles (tubera).(3) These tumors are rarely in- 
closed in a cyst, and are rounded. They are generally whitish, sel- 
dom red or brown. They vary in size from three to four inches. They 
are frequently very numerous, being developed in the centre of the 
liver, which is otherwise healthy. Like most new formations, they are 

(1) V. Murat, Sur V hypertrophic dufoie ; in the Bull, dc la soc. mid. d'emul, 
September, 1821. 

m VMurat!* moyens de dislinguer entrc dies les diverse, affectum* du foie 
denies sou* les rums do lubercules slrofuleux, d'hydaiides, *^*"*£ *£$% 
phi* enkystte, gtniralement confondues sous le nom ^obstructions , in the Hull, ae 
lasocmtd. d'tmul, September, 1821. 



312 i lUI'TIvr. ANATOMY. 

generally alburniaous.(l) Those, however, which have a brownish 
tint, appear from some recent experiments, to be more analogous with 
gelatine. (2) The diseases they resemble are principally scrofula or 
fungous haematodes. 

All the anomalies in the mass, size, and consistence of the liver 
hitherto mentioned, all the accidental formations mentioned in this 
gland, supervene principally after the immoderate use of ardent spirits. 
As they render the liver unfit for the secretion of bile, or prevent the 
excretion of that which it forms, they frequently occasion jaundice. 
This affection depends on a deposition of bile in a greater or less num- 
ber of organs and fluids, particularly in the skin. It may also be de- 
termined by the adjacent organs, and sometimes we discover no altera- 
tion to which it can be attributed. 

From the important functions of the liver, and also the intimate con- 
nection between it and the mind, this organ varies more or less in all 
general chronic and in all mental affections. 

Entozoaries are developed in this gland more rarely. The animals 
most commonly found there are hydatids, which occur in the liver more 
frequently than in any other organ ; they are extraordinarily large 
and numerous, and form very rapidly ; they are generally developed 
in one point, rarely in several, and most commonly in the right lobe. 
They are commonly separated from the healthy substance of the organ 
by cysts, usually formed by several layers. They not unfrequently 
destroy the liver to a great extent, and quitting the place where they 
are formed, generally proceed outward, most commonly by entering 
into the intestinal canal, more rarely into the chest and lungs, some- 
times even directly through an opening in the common integuments. 

Biliary concretions are more rare in the liver ; probably they al- 
ways form in the biliary passages, whence they afterwards pass into 
the substance of the gland. 

B. BILIARY PASSAGES. 

§ 2233. Sometimes, but rarely, a part of the biliary passages, par- 
ticularly the gall-bladder, is deficient(3) from a primitive deviation of 
formation, although this anomaly does not necessarily exercise an in- 
jurious influence on the health, which is less astonishing, since, accor- 
ding to the experiments of Merlin, the gall-bladder may be extirpated 
in cats without inconvenience, and it is normally absent in many 
animals. On the contrary, the entire absence of the biliary passages(4) 
is always attended with the most fatal results. 



(1) Portal, p. 95, Des obstructions albumincitscs dufoic. 

(2) Portal, p. 98, Des obstructions gelatineuses dujbie. 

(3) Ollivier, Note sur ['atrophic de <a vcsiculc biliare ; in the Archiv. gen, de ?ncd., 
vol. v., p. 1 96. 

(4) Home, Phil, trans., 1513, pt. ii., p. 146-159. 



OF THE DIGESTIVE SYSTEM. 313 

We rarely also meet in the biliary passages deviations of formation 
in regard to the quality, such as the existence of hepalo-cyslic duels 
(d. hepato-cyslici), going directly from the lower face of the liver into 
the gall-bladder, the slow union of the two roots of the hepatic canal, 
the opening of one or more branches into the cystic canal, or even into 
the gall-bladder, the insertion of the ductus choledochus in a point 
different from the intestinal canal, or even in the stomach. 

Of all the biliary passages, the gall-bladder most frequently presents 
anomalies of this kind, since when it is divided by a contraction into 
two cavities, placed successively in a longitudinal direction, or, as is 
more rare, when a longitudinal septum divides it into two parts adapted 
one to the other. The enlargement and the contraction of the biliary 
passages generally depends on mechanical causes, among which we 
must place first the biliary calculi contained within them, next, as is 
more rare, the engorgement of the lymphatic glands, which compress 
it from without inward.(l) The gall-bladder may be contracted 
or dilated by the calculi within it. The contraction and the total obli- 
teration of its cavity occur when a few or small calculi prevent by their 
situation the bile from entering it. On the contrary, numerous or large 
calculi, either alone or. together with the bile, often dilate the gall- 
bladder considerably when they are so situated as not to prevent en- 
tirely the entrance or departure of the bile, or when they exist in the 
ductus choledochus. Sometimes the gall-bladder is enormously dis- 
tended, simply by an increased secretion of bile, without any mechanical 
obstruction ; the membranes of this latter are then generally thin, 
while in the opposite state they are very thick. Sometimes the calculi 
are separated by perfect septa. 

New formations rarely occur in the gall-bladder ; we must mention 
as such, however, the osseous plates sometimes developed on the 
outer face of the mucous membrane, and the hairs inserted on its inner 
face. 

(1) Andral (Observations sur V obliteration des canaux biliaires ; in the Archiv. 
gen. de med., vol. vi., p. 16) admits four principal causes of perfect or imperfect, 
transient or permanent obliteration of the biliary passages ; these are the obstruc- 
tion of their cavity by a foreign body, a compression upon their parietes by mem- 
branous folds and by tumors of different kinds, a spasmodic contraction independent 
of all inflammation, and an inflammation followed by the engorgement of the mu- 
cous membrane and its thickening. He remarks that the first two causes are fre- 
quent, that in most cases the third has rather been supposed than demonstrated, and 
that physicians have not yet attended to the fourth. The latter, however, seems to 
be, if not always, at least very frequently, a consequent of a gastro-intestinal inflam- 
mation ; it is not unusual, and we have every reason to think that it always exists 
in the cases where the nerrous pathology led one to suppose the third. Like all in- 
flammations, that of the biliary passages, whether acute or chronic, is attended with 
the thickening of the parietes of the canal, which is finally changed into a ligamen- 
tous cord. F. T. 



314 nnscrurrivE anatomi 



§ 2234. The bile is often abnormal in its physical and chemical 
qualities, although we cannot always discover a certain connection 
between its anomalies and the state of the liver. It however seems 
less bitter when this organ is changed into fat. 

The most striking anomaly is that resulting from the presence of 
biliary calculi.(l) 

These concretions, which are found in aged persons, or in those who 
lead a sedentary life, differ from each other in situation, composition, 
color, number, size, texture, form, and consistence. 

1st. Situation. The biliary calculi generally occur in the gall-blad- 
der, so that they seem to be developed in this organ. They have 
been found also in the biliary passages, in the substance of the liver, 
although proportionally very rarely. Sometimes also they are situated 
in the hepatic or cystic canal, or in the ductus choledochus, but they 
finally fall into the gallbladder. Not unfrequently they leave the 
ductus choledochus and pass into the intestinal canal. 

The rarest case is where they occur out of the cavity of tire bili- 
ary passages in the substance of the liver, or in the membranes of the 
gall-bladder. The former may be formed in the place where they 
occur ; but the second are doubtless primitively developed in the cavity 
of the gall-bladder, and afterwards glide between its membranes, and 
are then inclosed by the closing of the opening which at first existed, 
although it is admitted they are formed in the place even where they 
are observed ; and this fact has even been cited to prove that the bile 
is partially secreted by the glands of the gall-bladder. (2) 

The justice of our etiology is demonstrated by the fact, that calculi 
are sometimes found in the depressions of the gall-bladder, which case 
is evidently intermediate between that where they are entirely loose in 
the cavity, and where they are situated on the outside of it and en- 
circled in the membranes. 

2d. Chemical composition. The chemical composition of the biliary 
calculi generally causes all those properties of which we have yet to 
speak. They are composed principally of two different substances ; 
one more or less dark in color and brownish, and the other white ; 
the latter is termed cholesterine. The bile contains none of it in the 
normal state. (3) The other is the yellow coloring substance of this 

(1) Vicq-d'Azyr, in the Mem. dc la soc. dc mid., 1779.— Fourcroy, Sur les ealculs 
des animaux ; in the Annates du Musium, vol. i.— S. T. Scemmerrinjr, De concrc- 
mentisbiliariis, Frankfort, 1793. — Mosovius, Diss, de calculorum animalium origine 
ct natura, Berlin, 1812. 

(2) D. G. Galeati, De caleulis in cysti felled ct intra ejus tunicas rcpertis ; in the 
Comm. Bonon., vol. i., p. 354.— Id., Dc cyelis fellece duclibus, same journal, vol. i , 
pt. ii., p. 331. 

(3) Chevreul has detected it in the bile of man and several animals (Note sur la 
presence dc la cholestirine dans la bile de Vhvmme; in the Jowrn. dephysiol. exp&r., 
vol. iv\, p. 267). p 'j\ 



OF THE DIGESTIVE SYSTEM. 315 

ie cholesterine probably arises from the change of a peculiar 
which exists in the bile, 
lliary calculi also contain a little of bile, which is easily sepa- 

it by water, 
rely find carbonate of lime on their surface.(l) 
^olor. These concretions are more or less colored from the 
yellow to the deepest dark brown, because they generally 
the substances mentioned above. Those only which are 
of cholesterine are entirely white, and they are very un- 
ion. Farther, the tint varies in the different parts of a biliary 
flus. 

Number. It varies from one to several hundreds. The calculi 

id of pure cholesterine are usually single, or at least very few. 

Volume. It varies no less than the number, and usually in an 

ratio. The calculi of pure cholesterine are generally larger than 

•compound concretions. Not unfrequently one of them fills the 

-bladder, and even distends it. 

kh. Form. The biliary calculi are generally more or less round ; 
Jse of pure cholesterine are more oblong. Their form is modified 
by (heir number, since the friction between them renders their 
rface smooth. Hence why those of cholesterine are generally 
re corrugated than the others ; but these concretions rarely pre- 
Pent sharp points. 
7th. Their texture varies. 

a. The biliary calculi are generally full and solid ; we, however, 
have one which is hollow. 

b. They are formed of several superimposed and differently co- 
lored layers, 

c. These layers are sometimes, though rarely, composed of one of 
the two substances mentioned above. In the contrary case they are 
all colored, and differ only in their shade of color. We not unfre- 
quently find externally an entirely white layer. 

d. The light colored layers have generally more or less evidently 
a radiated and fibrous texture. It is often easy to see that they are 
formed of very oblong pyramids slightly connected with each other, 
the summits of which converge towards the centre. This form seems 
to depend on the cholesterine, for it is never more apparent than in the 
calculi formed by this fatty body, and it decreases inversely with the 
color. 

e. Consistence. Biliary calculi generally are neither very hard nor 
solid. They are much softer and more brittle than the urinary con- 
cretions. Sometimes, however, they are considerably hard. Those 
of pure cholesterine are generally harder than the others, being even 
very firm and solid ; but they are frequently also very soft, while 
others which are more deeply colored are considerably hard. 

(1) London mcd. repository, vol. iv., p. 469. 



316 DESCRIPTIVE ANATOMY. 



II. PANCREAS. 

§ 2235. The pancreas(l) is the largest of the salivary glands. Its 
weight and size are three or four times those of the parotid gland, as 
it is six inches long and one thick, and weighs from four to six ounces. 
It is oblong, and is situated transversely at the upper part of the abdo- 
minal cavity, before its posterior wall, in front of the first and second 
dorsal vertebra, behind the stomach. Its left extremity generally 
touches the spleen and the left kidney. It passes before the aorta, and 
its right extremity is situated between the upper and lower folds of the 
duodenum. 

It is included between the two layers of the transverse mesocolon, 
which slightly adheres to its upper part, and does not cover it poste- 
riorly: 

Its figure is that of a hammer, since it enlarges at its right extremity, 
from whence proceeds an inferior prolongation, which embraces the 
duodenum posteriorly, and on the left, and even a little forward. The 
lower prolongation is called the head, and the transverse larger portion 
the tail. 

§ 2236. The pancreas is attached to the adjacent parts by a very 
loose cellular tissue, and enveloped by a thick layer of the same ; it 
has no special capsule. We also distinguish through the cellular en- 
velop, the lobes which unite to form it. 

These lobes can be divided into extremely minute lobules, attached 
by a very loose cellular tissue. 

The pancreas is yellowish brown, and rather firm in its texture. 

§ 2237. A considerable excretory duct passes entirely through this 
organ ; it is white and solid, and is called the pancreatic canal (ductus 
pancreaticus),(l) or the canal of Wtrstmg (ductus JVirswigianus). 
This canal arises at its posterior extremity by the union of several 
branches, which anastomose at an acute angle. In its course it re- 
ceives at a right angle, both a.bove and below, a considerable number 
of other branches, which may be easily followed by smaller granula- 
tions, so that it gradually increases in volume, and finally becomes a 
line and a half in diameter. Just before quitting the gland, it also re- 
ceives one or more very large twigs, which arise from the head, and 
which also open separately into the duodenum. 

This canal is not visible on the surface of the gland, which must be 
cut across in order to see it. 

(1) Brunner, Exp. nova circa pancreas, Amsterdam, 1633.— Graaf, Dc succo pan- 
creatico, Lcyden, 1664. — Johrenius, De aff'tcl. hypochondriacis, Rinteh), 1(578.— J. 
M. Hofl'mann, De pancreate, Altdorf, 1706.— J. D. Santorini, Tabula: septemdeeim, 
tab. xiii. 

(2) J. G. Winning, FSgura ductus cvjusdam, cum mulliplicibus suis raynuli* 
noviter in pancreate, in diversU corporibaa humanis obacrrali, Padua, I' 



OF THE DIGESTIVE SYSTEM. 317 

It generally opens into the duodenum, three or four inches below 
the pylorus, but sometimes much lower down, and even ten inches 
from it. 

In the place where it communicates with the duodenum, it unites 
externally with the ductus choledochus, but the two cavities remain 
perfectly distinct, even when proceeding side by side through the mem- 
branes of the intestine. They open side by side near the pancreatic 
duct, a little to the left of the choledochus, at the base of a small cavity 
about two lines long, the membrane of which has all the characters of 
the inner tunic of the duodenum, so that we cannot properly consider 
them as having a common orifice. 

Near its orifice the excretory duct of the pancreas enlarges more or 
less, but contracts at its opening, although there is no fold similar to a 
valve in this or in any other part. The appearance of a valve at its 
opening depends only on the septum between it and that of the ductus 
choledochus. 

§ 2238. The pancreas, like all the salivary glands, and most of the 
glandular organs, is more developed in the early periods of life than 
subsequently. 

We have observed that its excretory duct very constantly presents 
a remarkable difference, as it is at first double, that is, beside the 
permanent valve, there is then a second, which opens separately into 
the duodenum.(l) 

§ 2239. The congenital anomalies of this gland extend principally 
to the arrangement of its excretory duct, which sometimes seems 
double ; this state must be considered as a permanence of that in the 
fetus. (2) 

The most remarkable consecutive anomalies are induration and hy- 
pertrophy. We more rarely find in its excretory duct, calculi,(3) 
composed of phosphate of lime and of an animal substance. 

III. SPLEEN. 
A. PERFECT STATE. 

§ 2240. The spleen (splen, lien)(4) is situated in the left hypochon- 
drium, between the great cul-de-sac of the stomach, the lumbar portion 

(1) Meckel, Abhandlungen, p. 331, 353, 366, 380. 

(2) Tiedemann, Sur 'les differences que Ic canal excreteur du pancreas pretente 
dans I'hommeet dans les mammife'res ; in the Jou.ru. compl. des sc. med., vol. iv. p. 
370. „ , , .. , 

(3) Baillie has figured a remarkable case of it. (Engravings, fasc. v. tab. yn.) 

(4) F. Schuyl, Denature, et usu lienis, Leyden, 1664.— Malpighi, De hene ; mDe 
structura visccrum. — C. Drclincourt, De lienosis, Leyden, 1693.— G. St ukcley, TVie 
spleen, its description, uses, and diseases, London, 1723.— J. G. Duvernoi, Dehcne ; 
in the Comm. Petrop., vol. vi. p. 156.— S. T. Quellmalz, De Hene, Leipsic, 1748.— C. 
L. Rolof, Dc fabrieaetfunctione lienis, Frankfort, 1750.— Lassone, H^tnre anato- 
miaue dc la rale ; in the Mem. de Paris, 1754.— Werlhof, Dc splents usu, Wolfenbuttel, 
1761.— J- F. Lobstein, Dc Hene, Strasburg-, 1774.— J. P. P. Assolant, Recherches sur 

Vol. 111. 41 



318 DESCRIPTIVE ANATOMY. 

of the diaphragm, the commencement of the descending colon, and the 
left renal capsule, which it covers anteriorly. Its form is elliptical ; its 
posterior or external face is convex ; the anterior or internal is con- 
cave, and divided by a longitudinal groove called the fissure of the 
spleen (hylus Uenalis), into two halves, an anterior, which is the larger, 
and a posterior. Its upper extremity is a little thicker than the lower ; 
a fold of the peritoneum unites it to the diaphragm, the stomach, and 
the descending colon. 

It varies much in size, not only in different individuals, but also in 
the same individual at different periods, and inconstantly. In general 
we may say, that in the adult it is about four inches long, three broad, 
and a little less than one thick. 

Its weight varies as much as its size. Its mean weight is eight 
ounces, so that in the adult it is to that of the whole body as .1 : 210. 
But the volume and the weight of this organ are not necessarily in 
an inverse ratio with the distension of the stomach, as has been 
asserted.(l) Its specific gravity, compared with that of distilled water, 
is as 1.200 : 1000. 

It is of a brighter or darker red. 

The consistence of the spleen is slight ; it is also very soft. 

§ 2241. At first view the spleen seems formed entirely of blood-ves- 
sels, of which the arteries come from the cceliac trunk and the veins 
rest directly on the surface of the artery, and are proportionally larger 
than in any other part of the body ; they empty into the vena-portae, 
and carry there a very dark blood. The substance of the organ is sur- 
rounded by a very firm sero-fibrous membrane. The external layer 
is serous and comes from the peritoneum, with which it is continuous 
by two prolongations mentioned above. 

The fibrous layer belongs properly to the spleen, but it can be se- 
parated from the serous membrane only to a slight extent in the fis- 
sure. 

Numerous layers and very minute solid fibres proceed from it, which 
interlace in many different ways, and enter the space circumscribed by 
the capsule, leaving between them irregular spaces, in which the 
splenic vessels are distributed. 

These productions form, properly speaking, the base of the tissue of 
the spleen. 

Beside these fibres, other hollow canals proceed from the inner mem- 
brane of the spleen to its fissure ; these closely envelop the vessels, 
and unite with them. The first filaments are attached to the outer 

la rate, Paris, 1801. — A. Moreschi, Sul vero e primario usu della milza, Milan, 1803. 
— E. Home, On the structure and use of the spleen ; in the Phil, trans., 1808. — C. F. 
Heusinger, Leber den Bctu und Verrichtung der Milz, Thionville, 1817. — P. Gell- 
haus, Inaugural Abhandlung uber den Nut~e.nl der MHz, Wurzburg, 1817. — G. M. 
Felici, (Jsservazioni jisiologiche sopra lefunzloni delta milza, Milan, 1818.— I. Doel- 
linger, Betrachtungen uber die MHz ; in the Deutsche* Arckivfwr die Physiologic, 
vol", vi. p. 155.— Jseckel, Etwas uber die Verrichtung der MHz ; same journal, vol. vi! 
p. 581.— Hodgkin, Sur lesfoncliona de ta rale ; in the Jourru compl. des sc. vied., vol. 
xiv. p. 89. — Home, in the Phil, trans*, 1821, p. 25. 
(1) Assolant. loc. cit., p. 129-133. 



OF THE DIGESTIVE SYSTEM. 319 

face of these canals in the same manner as to the inner face of the 
fibrous capsule. 

The splenic arteries give off in their course numerous branches, 
which divide into very minute ramuscules, arranged like the bristles of 
a brush, but they do not anastomose together. On the contrary, the 
veins which surround these arterial fasciculi, frequently anastomose 
with each other, and with the adjacent veins. There are, however, 
no great communications between the arteries or the veins of the dif- 
ferent regions of the spleen. Those between the veins and arteries are 
very large, as may easily be seen by the aid of a microscope, or by the 
facility with which injections pass from the arteries into the veins. 

Besides the blood-vessels, the spleen also possesses numerous lym- 
phatics. Its nerves come from the splenic plexus, and are very small. 
They are scarcely one twelfth as large as the arteries they surround, 
and we cannot trace them far within the organ. Beside these consti- 
tuent parts, which several anatomists assert are the only ones, 
the spleen also contains, according to the more correct observations of 
others, particularly Malpighi, Ilewson, Dupuytren, Home, Heusin- 
ger, and Meckel, very many rounded, whitish, and very probably 
hollow, or at least veiy soft corpuscles, which differ much in respect 
to size and situation ; their size varies from one sixth of a line to one 
line, and they are sometimes near, and sometimes rather distant 
apart. 

These corpuseles are very intimately connected wtth the rest of the 
tissue of the spleen, and receive many blood-vessels; according to 
Home's observations, confirmed by those of Heusinger and our own, 
they swell much in animals when they drink. 

Malpighi considers them as glands. Ruysch and several other ana- 
tomists have denied their existence, and have asserted, but wrongly, 
that they are only simple fasciculi of vessels. 

Although neither these corpuscles, nor the spleen, have excretory 
ducts, they very probably contribute much to the changes of the blood 
in passing through this organ, and assist in forming the gastric juice, 
but particularly the bile. 

The substance of a reddish brown, easily separated by washing and 
pressure, should be regarded not as a constituent part of the spleen, 
but as the blood changed by this organ. 

The cellules heretofore admitted in the spleen, were very probably 
produced by the destruction of a part of the vessels, and of the internal 
fibrous tissue, by injections made with too much force, whence were 
formed spaces which are afterwards distended by inflation. 

§ 2242. As the spleen has no excretory duct, its functions are very 
obscure, and the more so, as it has frequently been extirpated without 
producing any constant or very great derangement in any function. 
Even at present, after so many experiments infinitely varied, after so 
many observations and reflections, wc can only hazard conjectures on 
this subject. Wc may, however, conclude from facts hitherto known, 



320 DESCRIPTIVE ANATOMY. 

that the spleen is intimately connected with the functions of the liver 
and stomach, and acts in concert with these two organs. 

That it assists in the functions of the liver, is proved by the fact, 
that all the blood which passes through its tissue, is carried to this 
organ by the trunk of the vena porta?. Hence, we may conjecture, 
and very probably, that the blood is changed within it, and rendered 
more proper for the secretion of bile, which conjecture is not contra- 
dicted by chemical experiments, from whence it has been concluded, 
that the blood of the splenic veins does not differ from that in the other 
veins. Possibly, also, the spleen contributes mechanically to increase 
the secretion of bile, since, during abstinence, a greater or less quantity 
of blood collects there, which is afterwards expelled by the pressure of 
the stomach when filled with food, and then goes toward the liver. 
But as the blood is not merely circulated in the spleen, but there under- 
goes some change, it follows, that the relation is not mechanical only, 
but also chemical. 

The spleen receives less blood at the commencement, of digestion, 
because the stomach, which is then full, prevents the blood from flow- 
ing freely into it ; but in proportion as the contents of the stomach pass 
out from it, the blood flows more easily to the spleen, and the function 
of this latter, in regard to the liver, becomes more active. Probably 
also the spleen concurs in the accessory function attributed above to 
the liver, that of neutralizing and assimilating foreign substances in- 
troduced into the body. Hence we must consider it as a viscus which 
performs, in regard to the vascular system, particularly to the liver, 
the same part as the conglobate glands towards the lymphatic system. 
It is more analogous to these glands than to the liver, as it has no 
excretory duct. The liver then appears as an organ composed of a 
conglomerate and a conglobate gland in the vascular system. 

The action of the spleen may also relate to that of the stomach in 
several different respects : 

1st. In a dynamical respect, since the two organs seem to be op- 
posed to each other, and the soft and blackish spleen may be consi- 
dered, from its substance and the change of the blood which passes 
through it, as contributing particularly to produce hydrogen, while 
the stomach is an organ which, from the nature of its secreted fluid, 
tends particularly to produce oxygen. 

2d. In a mechanical respect, as the spleen attracts the blood to it 
when digestion is not going on, while it receives less when this viscus 
is full, so that the blood flows in greater quantity toward the latter, 
that is, precisely at the period when most necessary to the secretion 
of the gastric juice. 

The function of the spleen seems also to be to receive promptly at 
least a part of the liquids introduced into the stomach, although this 
function does not belong exclusively to it, since after it has been extir- 
pated the liquids disappear as quickly as before, and the substances 
contained in this viscus reappear in certain fluids. 



OF THE DIGESTIVE SYSTEM. 321 



B. DIFFERENCES DEPENDING ON DEVELOPMENT. 

§ 2243. At first the spleen does not exist. It begins to appear dis- 
tinctly during the second month of gestation. 

It is at first infinitely smaller in proportion to the body, and parti- 
cularly to the liver, than it is subsequently, although it wrinkles and 
also wastes in old age. 

The whitish corpuscles are proportionally larger and more visible 
during the latter periods of fetal existence and in infancy than during 
the successive periods. 

All these peculiarities are very important, as they support the eighth 
law established in our introduction. In fact the spleen does not exist 
in the mollusca which have a liver ; it becomes proportionally smaller 
and smaller as we descend from the mammalia toward the lower 
classes of the animal kingdom ; and in most mammalia, as also in 
several other animals, the corpuscles are regularly larger in proportion 
than in man. 

C. ABNORMAL STATE. 

§ 2244. Among the anomalies of the spleen we must distinguish 
particularly some deviations of formation,(l) which deserve to be no- 
ticed. 

This organ is very rarely deficient from a primitive deviation of forma- 
tion in a subject where the formation is otherwise normal, while it is 
generally absent in cases of acephalia vera. 

A deviation of formation almost peculiar to the spleen, or at least 
observed in it more frequently than in any other organ, is its division 
into several spleens termed accessory (licnculi, s. lienes accessorii). 
These accessory bodies are always situated on the inner face, and 
generally toward the lower extremity of the spleen. 

They are usually, but not always, rounded, and vary in number 
from one to twenty-three. The latter number, however, has been ob- 
served only once, and we rarely find more than one supernumerary 
spleen. 

The great number of these accessory spleens is usually attended 
with other deviations of formation. This occurred in a subject who 
had twenty-three. (2) In another case, where there were seven, all 
the organs of vegetative life were at the same time inverted. (3) In a 

(1) C. S. Heusinger, Mcmoire sur les monstruositis de la rate produites par le 
difind de divcloppement de ce visccre ; in the Journ. compl. des sc. vied., vol. x., 
p.'21G. 

(2) Otto, JIandbuch der pathologischen Anatomic, p. 302. 

(3) Heusinger, loc. cit., p. b2. 



322 DESCRIPTIVE ANATOMY. 

third, where there were four, the foramen ovale of the heart was open 
to some extent.(l) 

The accessory spleens vary much in size. 

The existence of a great number of fissures which are frequently 
very deep on the anterior edge of the spleen, particularly toward its 
lower extremity, or of a more, or less distinct transverse fissure, which 
passes over its whole external face, form a remarkable intermediate 
degree between this anomaly and the normal state. 

Among the accidental deviations of formation, one consists in an 
enlargement of the spleen, usually attended with induration, which 
commonly arises from the metastasis of a general disease. (2) 

We not unfrequently find the spleen unusually hard withour en- 
largement or very soft. The latter exists particularly in diseases 
attended with great debility. 

New formations are rarely developed in the spleen. The tubercles 
sometimes seen in it are probably white corpuscles somewhat enlarged. 
Perhaps we should consider a special formation a solid uneven yel- 
lowish white mass which is frequently developed in the spleen. It, 
however, seems to be very similar to fungus hoanatodes. 

The capsule of the spleen frequently ossifies, particularly in ad- 
vanced age, to such an extent even that when the osseous substance 
has acquired a certain thickness in proportion to which the organ 
always wastes, we are led to think that the spleen itself is changed 
into bone. 



ARTICLE FIFTH. 

VESSELS AND NERVES OF THE ABDOMINAL PORTION OF THE 
DIGESTIVE ORGANS. 

§ 2245. The vessels of the most important and the largest part of 
the digestive organs mostly arise from three trunks, the cceliac, and 
the superior and inferior mesenteric arteries, which come directly from 
the abdominal aorta, and anastomose very frequently together. The 
lower extremity of the rectum also receives some branches from the 
hy pogastric artery. 

The veins, if we except those of the lower part of the rectum which 
empty into the iliac veins, unite and form the vena-portac, so that all 
the blood that returns from these organs passes through the liver be- 
fore going to the heart, and from thence into the lungs. 

(1) Baillie, Phil, irans., vol. lxxviii., p. 350. 

(2) C. F. Heusinger, Leber die Enlzundung und Vcrgrosserung dcr MHz. 
Eisenach, 1820. — S. Grottanelli, Ad acuta et ceronicw aplenihdia historiam animad- 
versiones, Florence, 1821.— C. H. Sclimid, Commcnlatio dc palhologia lienis, Got- 
Unpen, 1816. 



OF THE ORGANS OF VOICE. 323 

The nerves come principally from the great sympathetic nerve. 
Those of the stomach, however, arise chiefly from the pneumo-gastric 
nerve, and those of the rectum from the sacral pairs. 



CHAPTER II. 

ORGANS OF VOICE AND RESPIRATION. 

§ 2246. In the preceding chapter on the systems we described the 
digestive organs which belong to vegetative life ; these appear earliest 
in animals, or in the fetuses of animals, perform at first the functions 
of all the rest, and are the type on which these latter are formed, which 
are, however, less perfect and much less complex. We now proceed 
to describe the respiratory organs, in which the nutritious fluid formed 
in the first is in general perfected. 

The vocal apparatus is so connected with the organs of respiration 
that it occupies the summit of the canal by which these latter commu- 
nicate with the air by the cavities of the nose and mouth, and it is in 
fact only a development of the upper extremity of this canal. It is 
then most convenient to begin with it. 

ARTICLE FIRST. 

ORGANS OF VOICE. 

§ 2247. The organs of voice(l) are composed principally of the 
larynx, in which the voice is formed, although it is modified in differ- 
ent modes when passing through the cavities of the nose and mouth, 
which are situated before it. 

I. LARYNX GENERALLY IN THE PERFECT STATE. 

§ 2248. The lanjnx is an oblong, quadrangular cavity, formed of 
several cartilages, of ligaments which unite them, of muscles which 

(1) Galen, Vocalium instrumeniorum disscctio: in the Opp. ovin. — Fabric i us of 
Aquapcndente, De visione, voce, etauditu: Id., Delaryngc vocis inslrumento : in the 
Opp. omn. — J. Casserio, De vocis auditusque organis, Fcrrare, 1600. — D. Santorini, 
De laryngc ; in the Obs. anat., c. vi.— A. P. Walther, De laryngc et voce, Leipsic, 
1740. — R. A. Vogel, De larynge humano et vocis for matione, Erfurt, 1747. — J. G. 
Runge, Devocc ejusque organis, Lcydcn, 1753. — Herissant, llecherches sur les or- 
ganes de la voix des quadrupedes et de cclle des oiscaux ; in the Mini, de Paris, 
1753.— J. M. Busch, De mcchanismo organi vocis h ujusque functionc, Groningen, 
1770.— Vicq-d'Azyr, De la structure des organcs qui serrent a la formation dc la 
voix, considerec dans Phomme cl dans lea dvff&xntes classes d'animaux: in the 
mm. de Paris, 1779, p. 178-206.— J. Wolff, Diss, dc organo vocis mammalium, 
Berlin, 1812. 



321 DESCRIPTIVE ANATOMY. 

move them, and of a mucous membrane which covers them in every 
part, after which it is continuous upward with the buccal membrane, 
below with that of the trachea. This cavity gradually contracts a 
little from above downward. It is situated at the upper and anterior 
part of the neck, below and behind the lower jaw, between the trachea 
and the cavities of the nose and mouth, of which it is the direct conti- 
nuation. 



A. CARTILAGES OF THE LARYNX. 

§ 2249. There are nine cartilages which form the base of the 
larynx, three of which are unmated and six exist in pairs. The pairs 
are situated on the sides ; the unmated are divided by the median line 
into two equal halves, a right and a left. 

The unmated cartilages are the largest, and principally form the 
whole larynx. They are the thyroid and cricoid cartilages, and the 
epiglottis. The pairs are the arytenoid, the rounded, or the tubercles 
of Santorini, and the cuneiform cartilages. 

I. THYROID CARTILAGE. 

§ 2250. The thyroid cartilage (C. thyroidea), the largest of the car- 
tilages of the larynx, forms its upper and anterior part, produces at the 
upper part of the neck, a prominence called Adam's apple. It is an ob- 
long quadrilateral plate, more broad than high, and composed of two 
lateral halves, which unite forward on the median line, where the angle 
they form is more acute in the male than in the female. Hence this 
layer is very convex forward and very concave backward, where it is 
open. 

Its upper edge is very convex ; it however presents in its centre a 
deep groove, so that the cartilage is lower in this place. 

Its lower edge is Very convex : it is formed on each side of two 
superficial grooves, separated by a median prominence. 

The posterior edges are loose ; they extend upward and downward 
into two elongated horns, which are rounded and turned backward 
and which are distinguished into upper and lower. The upper horns 
are longer and thinner than the lower. 

We observe on the outer face of the cartilage at the base of the 
upper horn a considerable triangular prominence, whence arises an 
oblique line which descends from behind forward to the lower edge 
and which separates the posterior sixth of each half of this external 
face of the five anterior sixths. 



OF THE ORGANS OF VOICE. 325 



II. CRICOID CARTILAGES. 

§ 2251. The cricoid cartilage (C. cricoidea, s. anntdaris), which 
forms the lower part and a portion of the posterior part of the larynx, is 
circular, as its name indicates, and about three times higher posteriorly 
than anteriorly. It is convex forward, and on the sides are depres- 
sions which render the surface corrugated, and on its upper edge is a 
sharp prominence which inclines outward. 

The posterior part is irregularly quadrilateral and broader below 
than above. Its anterior face is uniformly concave ; the posterior jis 
loose and very prominent in the centre, especially below. • 

We there observe a depression on each side, and it presents a plane 
articular facet where it unites with the side. 

Its upper edge also enlarges on each side into a plane articular facet 
which is inclined from above downward. 

III. ARYTENOID CARTILAGES. 

§ 2252. The arytenoid, triangular, or pyramidal cartilages (C. ary- 
toznoidece, s. triquetral, s. pyramidales) have an elongated triangular 
form. Their anterior face is convex and uneven, and divided by a 
transverse prominence into a superior and an inferior depression. 

The posterior has about the same extent as the anterior, and is 
concave. The internal is much smaller than the other two, and i3 
slightly convex. 

These two cartilages are fitted by their concave base to the sides of 
the upper articular facets of the cricoid cartilage (§ 2251). 

IV. ROUND CARTILAGES. 

§ 2253. On the summit of each arytenoid cartilage is a much 
smaller, and also triangular cartilage, termed the tubercle of Santorini, 
or the round or horny cartilage (comiculum, s. capilulum Santorinia- 
num),(l) the convex face of which looks forward, and the internal 
backward. Its lower face is concave, rests on the convex summit of 
the preceding, and is articulated with it by a loose capsular ligament, 
some fibrous ligaments of which add to its solidity. 

V. CUNEIFORM CARTILAGES. 

§ 2254. The cuneiform cartilages (C. cuneiformes) are slightly 
curved on themselves. Their bases are turned upward, and their sum- 
mits downward. They are situated in the centre of the membranous 
expansion extended between the arytenoid cartilages and the epiglottis. 

(1) Loc. tit., p. 97. 
Vol. HI. 42 



326 DESCRIPTIVE ANATOMY. 



VI. KFIULOTTIS. 

& 2255 The epiglottis (epiglottis, s. Ugula), a very soft cartilage, is 
nearly rhomboidal ; its lower part is pointed, and terminates by a su- 
perficial groove, and is situated directly above the groove of the upper 
edge of the thyroid cartilage. Its length exceeds its breadth, and it is 
much thinner from before backward than in any other direction, except 
at its centre. It presents numerous openings, through which pene- 
trate small muciparous glands, which open on these two faces. Its 
elasticity, and the ligaments to be described, cause it generally to lie 
perpendicular, and to rise towards the isthmus of the fauces : but the 
weight of the substances which pass on it, and the action of special 
muscles, depress it, so that it covers the entrance of the larynx. 

The epiglottis prevents the entrance of foreign bodies, especially 
the food and drink, from the cavity of the nose, and particularly the 
mouth, into the larynx. Although pathological observations, in regard 
to the absence of this cartilage,(l) and experiments, where deglutition 
has not been impeded by removing the epiglottis, when the nerves and 
muscles of the glottis were preserved, while it was very difficult when 
these nerves were divided, the epiglottis remaining entire ;(2) although 
all these facts(3) prove that the closing of the glottis also partially con- 
tributes to prevent the food from falling into the larynx, it does not fol- 
low that the epiglottis does not fulfill the function attributed to it by 
every physiologist since the time of Aristotle. This function, in regard 
to which we quote a lively, but perfectly correct remark of Casserio,(4) 
has been doubted by Magendie, whose opinion has been contested by 
Mayer, from observations carefully made upon himself. (5) 

(l)Targioni Tozzetti, Prima raccolta di osservazioni, Florence, 1752. — Magendie, 
Precis de physiologic, vol. ii. p. 63. 

(2) Magendie, mtmoire sur I'usage de Vepiglottc dans la diglutition, Paris, 1813. 

(3) C. T. F. Reichel (Diss, de usu epigloltidis, Berlin, 1816) has observed, con- 
trary to Magendie's assertion, that rcmovig the epiglottis always rendered deglu- 
tition difficult in those animals where it was removed. On this subject, Rudolphi 
mentions the case of a man who died of laryngeal phthisis, in whom the epiglot- 
tis was destroyed so that but a small portion of its base remained. This man 
found it very difficult to swallow : he was obliged to mix drinks with his food 
to form ahind of pulp, which was introduced into the stomach with difficulty. G. 
Sachse relates several cases, which prove that deglutition is always very much im- 
peded in laryngeal phthisis. (Beilrdge zur genauern Kenntniss und Untersckei- 
dung der Kehlkopfs-und Luftrbhrenschwindsuchten, Hanover, 1821). Farther, 
Rudolphi attributes to the epiglottis another use also : he thinks that this cartilage 
serves also in those animals who breathe through the nostrils, the mouth being 
closed, to favor the entrance of the air into the larynx, by presenting a more direct 
way than through the cavity of the mouth. F. T. 

(4) Loc. cit., De epiglotiide, c. xvii., Talis structura, tale qfficium, ut stupidus 
iUe, vecorsque dici mereatur, quern non corum. consideralio, atlonitum quasi, in ad- 
mirationem Dei rapiat. 

(5) Ueberdic Function des Kchldeckels, in the Salzburger Zcitung, 1814, vol. iii. 
p. 156. 



OF THE ORGANS OF VOICE. 



B. LIGAMENTS OF THE LARYNX. 



327 



§ 2256. The cartilages of the larynx are united with each other, 
and with the hyoid bone and trachea, by capsules, fibrous ligaments, 
and compact cellular tissue. 

I. SPECIAL LIGAMENTS. 
A. BETWEEN THE THYROID AND CRICOID CARTILAGES. 

§ 2257. The thyroid and cricoid cartilages are united by three liga* 
ments, a central or pyramidal, and two lateral. 

a. Middle crico-thyroid ligament. 

§ 2258. The middle crico-thyroid or pyramidal ligament {L. conoi- 
deum, s. thyreo-cricoideum medium), is short, fibrous, strong, and trian- 
gular. Its base looks downward, and its blunt summit upward. It 
fills the space between the centre of the lower edge of the thyroid car- 
tilage, and that of the upper edge of the cricoid cartilage. 

It prevents the cricoid and thyroid cartilages from separating from 
each other too far upward and downward. 

b. Lateral thyro-cricoid ligament. 

& 2259 The lateral thyro-cricoid ligament {L. thyreo-cricoideum 
laterale) is loose, composed of fibres, which are oblique from above 
downward, and situated between the lower horn of the thyroid carti- 
lage and the lower articular facet of the cricoid. 

Its uses are the same as those of the preceding. It. serves, however, 
also to confine the motions of the two cartilages forward and backward. 

B. LIGAMENTS BETWEEN THE THYROID CARTILAGES AND HYOID BONE. 

a. Middle thyro-hyoid ligament. 

5 2260 The middle thyro-hyoid ligament (L. thyreo-hyoideum me- 
dium) is a broad layer of compact cellular tissue, winch descends from 
fhe posterior edge of the body of the hyoid bone, to the rmddle groove 
of the upper edge of the thyroid cartilage. 



b. Lateral thyro-hyoid ligament 

„.<rf thyro-hyoid ligament (L. 
rale) is oblong, rounded, and formed of longitudinal fibres. 



6 2261. The lateral thyro-hyoid\\ g ^mmt(L. thyreo-hyoideum late- 
y .. .. .-, i .^.j r.r„ ,i ^n^rrWnriinnl fibres. It extends 



"2° DESCRIPTIVE ANATOWV. 

from the summit of the upper horn of the thyroid cartilage, to the ex- 
tremity of the great horn of the lvyoid bone. At about its centre, but 
generally nearer the upper than the lower edge, it contains a small 
rounded and oblong cartilage, or bone (C. tritica), which, in fact, be- 
longs to the class of the cartilages or bones of the tendons. 

C. LIGAMENT BETWEEN THE CRICOID AND ARYTENOID CARTILAGES. 

§ 2262. Each arytenoid cartilage is united by its lower face to the 
upper articular facet of the cricoid cartilage, by a loose synovial cap- 
sule, strengthened at intervals by ligamentous fibres. 

D. LIGAMENT BETWEEN THE ARYTENOID AND ROUND CARTILAGES. 

§ 2263. These two cartilages are united by a very loose, and often 
slightly apparent capsule, on the surface of which pass ligamentous 
fibres. 

E LIGAMENTS OF THE EPIGLOTTIS. 

a. Epiglotti-hyoid ligament. 

§ 2264. The epiglottis is united to the upper edge of the middle 
hyoid bone by a compact cellular tissue, termed the epiglotti-hyoid 
ligament (L. epiglotli-hyoideum) . 

b. Thyro-epiglottid ligament. 

§ 2265. The thyro-epiglottid ligament (L. thyreo-cpiglottideum) is 
strong and fibrous. It extends from the lower extremity of the epi- 
glottis to the groove in the upper edge of the thyroid cartilage. 

F. LIGAMENTS BETWEEN THE THYROID AND ARYTENOID CARTILAGES. 

§ 2266. We find on each side, between the arytenoid and thyroid 
cartilages, one above the other, two ligaments, directed from behind 
forward, from above downward, and from without inward, which are 
situated some fines from each other, and are termed the thyro-arytenoid 
ligaments {L. thyreo-arytenoidea). 

a. Inferior thyro-arytenoid ligament. 

§ 2267. The inferior thyro-arytenoid ligament (L. thyreo-arytenoi- 
deum inferius) ) is much larger than the upper, and is composed of very 
distinct fibres. It extends from the upper and prominent end of the 
anterior edge of the inner face of the arytenoid cartilage, to the lower 



OF THE ORGANS OF VOICE. 329 

part of the posterior face of the thyroid cartilage, and is attached in 
this place, directly at the side of its mate, above the groove of the 
lower edge. 

These two ligaments are generally more developed in the male than 
in the female, and are termed the vocal cords, or ligaments of the glot- 
tis (L. vocalia, s. glottidis), and the fissure between them is termed 
the glottis (glottis, s. rima glottidis). 

b. Superior thyroarytenoid ligaments. 

§ 2268. The superior thyro-arytenoid ligaments (L. thtjreo-arytenoi- 
deora superiorum, s. ventricula laryngis) are situated farther outward 
and upward, between the centre of the anterior face of the arytenoid car 
tilage, and the angle of the thyroid cartilage. Those of the two sides 
are more remote from each other, are looser and much less evidently 
fibrous than the two preceding. They are distinguished only because 
the mucous membrane of the larynx is reflected outward, and forms a 
depression between them and these latter. 

C. MUCOUS MEMBRANE AND GLANDS OF THE LARYNX. 

§ 2269. The larynx is covered internally by a reddish and smooth 
mucous membrane, which is uninterruptedly continuous above with that 
of the cavity of the mouth, and below with that of the trachea. The 
outer face of this membrane contains muciparous glands, which vary 
in size, and are united in bundles. One of these glands, the arytenoid 
(G. arylenoidea), is situated before the arytenoid cartilage. Another 
is larger, imbedded in the midst of fat, and is termed the epigloitid 
gland ( G. cpiglottidea) ; it occupies the space between the epiglottis, the 
tongue, and the hyoid bone. It opens by from twenty to thirty excre- 
tory passages, which pass through the epiglottis, and the origins of 
which are easily seen on the inner face of the mucous membrane and 
the epiglottis. 

§ 2270. The mucous membrane forms on each side a considerable de- 
pression, termed the ventricle ofthe'larynx (ventriculus laryngis). This 
depression is situated between the superior and inferior thyro-arytenoid 
ligaments ; it is at most but one line deep, and two broad. It extends 
then much farther from before backward, than in any other direction. 
It is covered below by a considerable number of muciparous glands. 

D. MUSCLES OF THE LARYNX. 

§ 2271. The muscles of the larynx are divided into those which 
move the whole apparatus, and those which move some of its carti- 
lages. 



330 DESCRIPTIVE ANATOMY. 



I. GENERAL MUSCLES OF THE LARYNX. 



§ 2272. The general muscles of the larynx are the stcmothyroideus 
and the hyo-thyroideus. 

a. Stcrno-thyroideus. 

§ 2273. The sierno-thyroideus muscle (M. bronchitis), is thin, ob- 
long, and considerably contracted from below upward. It arises from 
the posterior face of the handle of the sternum, and the inner part of 
the posterior face of the cartilage of the first rib, ascends directly before 
the trachea, covered by the sterno-hyoideus muscle, and is attached 
by an oblique edge, formed of very short tendinous fibres, to the oblique 
line of the thyroid cartilage. It is generally blended at its outer part 
with the thyro-hyoideus muscle, and it is cleft in a greater or less 
extent. 

Its external face generally presents, some distance from its lower ex- 
tremity, a transverse or oblique tendinous intersection. 

Sometimes there are two of these muscles placed one above the 
other.(l) It depresses the larynx, by acting on the thyroid cartilage. 
Its union with the following muscle causes it to depress the hyoid 
bone. 

b. Hyo-thyroideus. 

§ 2274. The hyo-thyroideus muscle has an oblong square form : it 
gradually contracts from below upward, and at the same time becomes 
thicker in the same direction. It arises from the oblique line of the 
thyroid cartilage, directly above the upper edge of the preceding, and 
ascends along the outer part of the lateral face of the thyroid cartilage, 
to arrive at the great horn of the hyoid bone, and is attached to the 
anterior part of the lower face. 

It raises the thyroid cartilage and the larynx, when the hyoid bone 
is fixed, and depresses it when the latter is not fixed, so that it con- 
tributes by the first of these two actions, to produce acute sounds, and 
by the second to deglutition. 

II. SPECIAL MUSCLES OF THE LARYNX. 

§ 2275. The special muscles of the larynx are those which dilate 
and contract the glottis. 

A. MUSCLES WHICH DILATE THE GLOTTIS. 

a. Crico-thyroideus. 

§ 2275. The crico-thyroideus muscle (M. crico-thyroideus, s. dila- 
tator glottidis anterior), is very small, and nearly rhomboidal, and its 

(1) Gunz, Obs. anal., in the Mem.pre's. a Vac. des $c, vol. i. p. 286. 



OF THE ORGANS OP VOICE. 331 

figure is a slightly inequilateral square. It is covered by the sterno- 
thyroideus muscle, and is situated between the lateral faces of the thy- 
roid and the lower edge of the cricoid cartilage. It arises from the 
lower edge and the lateral face of this latter. Its fibres are directed 
obliquely from below upward, and from before backward, and are often 
divided into two distinct fasciculi, an anterior and a posterior. It is 
attached by a short tendon to the lower edge, and the inferior horn of 
the thyroid cartilage. 

It is used to draw the sides of the thyroid cartilage downward and 
outward, so that it enlarges the glottis. 

b. Crico-arytenoideus. 

§ 2277. The crico-arytenoideus muscle (M. crico-arytcnoides, s. dila- 
tator glottidis posticus), is rhomboidal, and fills most of the posterior 
face of the cricoid cartilage. It arises from its whole extent, ascends 
from within outward, and is attached by a short tendon to the outer 
edge of the arytenoid cartilage. 

It draws this cartilage outward, turns it a little on its axis, and thus 
dilates the glottis, especially at its posterior part. 

B. MUSCLES WHICH DILATE THE GLOTTIS. 

a. Crico-arytenoideus lateralis. 

§2278. The crico-arytenoideus lateralis muscle is small, and of an 
elongated triangular form. It extends obliquely from before backward, 
and from below upward, from the posterior part of the upper edge of 
the lateral portion of the cricoid cartilage, to the lower part of the outer 
face of the arytenoid cartilage. 

b. Arytenoides obliquus et transversus. 

§ 2279. The arytenoides obliquus and transversus muscles being 
united very intimately, should be considered as forming a single mus- 
cle, the different layers of which do not follow the same direction. 

The oblique fibres form the two posterior and weaker layers. They 
arise from the lower part of the outer edge of the arytenoid cartilage, 
above the insertion of the crico-arytenoideus muscle, ascend obliquely 
towards the opposite side, and becoming broader and thinner, are 
attached to the outer edge of the arytenoid cartilage of the op- 
posite side. 

The fibres which come from the left arytenoid cartilage, usually 
cover those arising from the cartilage of the other side. 

The transverse fibres are partly covered by the preceding, and are 
attached by their two edges to the posterior face and the external edge 
of the two arytenoid cartilages. 



332 DESCRIPTIVE ANATOMY. 

All these fibres bring together forcibly, the tvo arytenoid cartilages, 
and thus contract 'the glottis, especially at its posterior part, m a 
transverse direction. 

c. Thyro-arytcnoideus. 

§ 2280. The thyro-arytenoideus muscle (M. thyro-aryhnoidewt) is 
very elongated ; it arises from the centre of the inner face of the thy- 
roid cartilage, from the pyramidal ligament, sometimes also from the 
lower part of the epiglottis, goes backward and a little upward, and is 
inserted at the lower part of the outer edge of the arytenoid cartilage, 
directly above the upper extremity of the crico-arytenoideus lateralis 
muscle, with which it is blended. 

Sometimes we observe, still higher, another and smaller synonymous 
muscle. 

These two muscles draw the arytenoid cartilage forward, and thus 
contract the glottis from before backward. They diminish the extent 
of the glottis more than any other muscle. The fibres which go to 
the epiglottis, are inserted in this cartilage. 

d. Thyro-epiglotticus. 

§ 2281. The thyro-epiglotticus, or the depressor cpiglottidis muscle, 
arises from the centre of the inner face of the thyroid cartilage, and is 
inserted on the lateral edge and the lower part of the epiglottis. 

There is sometimes a smaller one, which arises farther inward and 
upward. 

These two muscles depress the epiglottis. 

F. NERVES OF THE LARYNX. 

§ 2282. The nerves of the larynx arise from the pneumo-gaslric 
nerve, and are the superior laryngeal and the inferior laryngeal or re- 
current nerve. Both are distributed in the mucous membrane and in 
the muscles.(l) 

(1) Magendie (Physiologie, vol. i., p. 206) and Cloquct (TraiU d'anatomie, vol. ii., 
p. 622) think the first of these nerves goes wholly or nearly so to the crico-thyroidei 
posticus and laterales muscles, and also to the thyro-arytenoideus. Hence, whether 
the different muscles contract or dilate the glottis, they receive all their filaments 
from one of these two nerves, and completely dividing; or tying them, enfeebles the 
voice, which is entirely lost when both arc divided. Rudolphi (Physiologie, vol. ii., 
p. 375) remarks that this description is incorrect, and that we must adopt that of 
Andersch and Scemmcrring, whose neurology is followed by Meckel. In fact, the 
superior laryngeal nerve anastomoses by some twigs with the recurrent nerve within 
the larynx ; the two nerves send twigs also to the muscles which contract and dilate 
the glottis, and the recurrent nerve sends some to the crico-thyroidcus muscle. An- 
dersch (Tract, dc nervis hum. corp. aliquilnls, p. i., Koningsberg, 1797, p. 50) men- 
tions a case where the two nerves did not anastomose in the larynx, but expressly 



OF THE ORGANS OF VOICE. 333 



G. FUNCTIONS OF THE LARYNX. 



§ 2283. The mucous membrane of the larynx is extremely suscep- 
tible, on account of the great number of nerves which it receives, par- 
ticularly in the region of the glottis. This sensibility prevents foreign 
bodies from entering the trachea, where they would inevitably cause 
suffocation. It is curious that it is so developed only at Ihe upper 
part of the air-passages, and that the mucous membrane of the trachea 
does not possess it. 

The vitality of the larynx is manifested principally by its motions, 
which are of two kinds. In fact : 

1st. They extend to the whole system, or are confined to some of 
its component parts. 

2d. They move in several different cases, and are connected with 
several functions. 

The general motions of the larynx vary its relations with the adja- 
cent parts, according as it is drawn upward, downward, forward, or 
backward. The partial motions change the mutual relations of its 
constituent parts, and vary particularly the form and extent of the 
glottis. 

The whole larynx moves in speaking and deglutition. 

During deglutition, the larynx is drawn forward and upward, as we 
have already explained, which prevents the food from entering it. 

In speaking, the larynx rises in acute sounds, both to raise the thy- 
roid from the cricoid cartilage, and thus to contract the glottis, and at 
the same time to tense its ligaments, so as to lengthen and contract the 
trachea. In low tones, on the contrary, it is depressed to produce op- 
posite changes. 

The partial motions are connected with deglutition, respiration, and 
speaking. 

In fact, in deglutition, the glottis is so contracted by the action of its 
constrictor muscles, that, even were the epiglottis absent, the food 
would not necessarily and constantly fall into the air passages. 

In respiration, the glottis is dilated during inspiration, and contracted 
in expiration ; these changes constantly occur, even when the voice 

states that this is not the common arrangement. When it may be as true that it is 
not, says Rudolphi, that the constrictor muscles and those which dilate the glottis 
receive distinct branches from the par vagurn, what must we conclude ? One nerve 
causes the contractions in muscles which contract and those which dilate the glottis ; 
it is then unimportant which these muscles receive. But the fact that the same 
muscle receives twigs from the upper and from the lower nerve is very important, 
since the action may take place in one direction when a ligature or section prevents 
it in the opposite, and it is still more so as the pneumo-gastric nerve anastomoses 
above and below with the great sympathetic nerve, and above with the glosso-pha- 
ryngeal, the accessory, and the hypogastric nerves, so that the inner nerves of the 
larynx certainly come from several different sources. F. 1 . 

Vol. Ill 43 



334 PEscnirrivE anatomy. 

cannot be formed, on account of an opening in the trachea.(l) Far- 
ther, this is not surprising, since they coincide with analogous changes 
which supervene simultaneously in the trachea, of which the larynx 
must be considered the upper enlarged and more developed part. 

From Legallois' experiments the closing of the glottis is the cause 
of rapid death in suffocation, which occurs in certain cases from di- 
viding the pneumo-gastric nerve or the laryngeal branch, particularly 
in youth, -as in such states the glottis always appears very much con- 
tracted.^) 

The fact is correct, but the mode of explaining it by the paralysis of 
the arytenoidei muscles is only partially true. The contraction and 
even the closing of the glottis from the paralysis of the muscles to 
which the recurrent nerve is distributed, seems to depend rather on the 
predominance of the muscles, the nerves of which are unaltered, and 
therefore caused only in part by the paralysis. 

In fact in animals of a certain age, in which the operation is less 
dangerous on account of the size of the glottis, this opening is almost 
entirely closed after dividing the two recurrent nerves, while it is closed 
but imperfectly when the superior laryngeal nerves are cut, and the 
power of forming it is lost after separating all the nerves of the la- 
rynx.^) 

The special motions of the larynx are very remarkable in forming 
the voice. 

At each tone the glottis contracts, and the more the louder the tone 
is. (4) The contraction occurs particularly from one side to the other ; 
sometimes also from before backward, and often in every direction at 
once. 

§ 2284. The larynx is the organ of the voice. This is proved : 

1st. By the loss of voice, without any derangement in the respira- 
tion, when the trachea presents an opening through which the air 
enters and emerges in inspiration and expiration. 

2d. By the diminution or the total loss of voice when some parts of 
the larynx, as the vocal cords have been destroyed, or the arytenoid 
or cricoid cartilages, or the laryngeal nerves are divided. 

3d. By the differences in the voice, dependent on those in the ar- 
rangement of the parts of the larynx. 

The voice is formed in the glottis, since the power of producing it is 
lost when the crico-thyroid ligaments are divided, and the removal of 
the upper half of the arytenoid cartilages and the longitudinal section 

(1) Bichat, Anat. descript., 1802, vol. ii., p. 405.— Legallois, Exp. sur le principc de 
la vie, Paris, 1812, p. 198. — L. Mende, CJeber die Bewegurtg der Slimmritze beim 
Athemholen, eine neve Entdeckung ; mil beygefiigten Bcmerkungen uber den 
Nutzen und die VerriclUung des Kehldeckels i Gripswald, 1816. 

(2) Legallois, p. 197. 

(3) Magendie, Sur Vipiglotte, p. 4. 

(4) Ferrein (M<5m. de Paris, 1741, p. 559) has already opposed the opinion hitherto 
existing, viz. that, the contrary is true. Bichat has followed in the same track (Anal 
descr., vol. ii., p. 408). 



OF THE ORGANS OF VOICE, 



335 



of the thyroid cartilage produces the same effect, which is always ob- 
served in the contraction of the glottis in crying, as the destruction of 
the upper ligaments has no effect on the voice, and as these ligaments 
likewise are always too far from each other to contract the glottis(l) 
transversely. 

§ 2285. We have now to determine how the voice is formed in this 
place. Some suppose it is owing to the vibrations of the air, as in a 
wind-instrument.(2) Others assert that it is produced by the vocal 
cords, as in a stringed instrument. (3) Finally, several have combined 
these two theories. (4) 

The first has been supported : 

1st. By the analogy of the air-tube with a wind instrument, m 
which the formation of the different sounds is produced by modifying 
the diameter of the opening. 

2d. By the comparison with the lips, where the same conditions 

occur. 

3d. By different experiments proving : 

a. That the tension or relaxation of the vocal cords has no effect on 
the acute or grave character of the sound, inasmuch as the glottis is 
dilated or contracted by them. 

b. That when one of the vocal cords is tense and the other relaxed, 
they do not produce two different sounds, but one sound, the acuteness 
of which is proportional to the breadth of the glottis. 

c. That the tone does not change when we touch the vocal cords. 

d. That the contraction of the glottis is sufficient to render the tone 
more acute, and its dilatation to depress it, although the tension of the 
vocal cords does not change, and independent too of their form. 

c. That the sound is independent of the force with which the air 
leaves the lung. . . . 

f. That no tones are formed when the glottis is very much dilated, 
and the vocal cords are very tense, and the air is forcibly expelled from 
the lung.(5) 

(1) E. Grasinow has asserted (Russiche Jahrbucher, vol. ii., pt. i., P. 125-143) that 
the voice is formed in the trachea. Burdach has refuted tins absurd opinion (same 

^FabriSof Aquapendente, De larynge, p. ii, c iv. Vocis opifex, causa sen 
organum inquiritur.-C.Y. S. Liscovius, Diss, sistens theoriam vocis, Leipsic, 1814, 

(3) Ferrein, De la formation de la voix dans I'homme ; in the Mtm. de Paris, 1741, 

P '(4) 5 Galien, Devsu partium, voL viL p. lO.-Cas ^rio, Z?e Za ri/^e book i^ ch. 
xiv De sloitide — Dodart, Mtm. sur les causes de la voix de I'homme et de ses diffe- 
renitons; in the Mtm. de Paris, 1700, p. ^OS.-Id ^pl^ns^^emmressur 
la voixet sur les tons; same journal 1706 p. 169 and 500; 1707 p ^83 --Votex* 
however, attributes most influence to the vibrations of the air; it .6 then &f™* t0 
understand why modern physiologists, even neglecting F ^ K ™f*f*%wni "£ 
should maintain that Ferrein's opinion was the only one Emitted, and pres n the 
theory as new, and more so because Ferrein directly opposes the hypothesis ot 
Dodart. 
(5) Liscovius, loc. cit., p. 29-34. 



336 DEScniPTivr anatomy. 

The second theory is supported : 

1st. By the analogy of the vocal cords with stringed insfruments.(l) 
2d. By experiments which have proved that the extent to which the 
larynx was open had absolutely no effect on the acute or grave charac- 
ter of the sound,(2) while, on the contrary, the tone became acute as 
the vocal cords were carried outward and extended by the air leaving 
the lung, and was lower when the ligaments were compressed ; that it 
is modified in the same manner when these ligaments are fixed on se- 
veral points ; that the different tones are produced when the degree of 
tension of the ligaments varied ; finally, that similar phenomena occur 
when the ligaments of the larynx are entirely detached, except at 
their two extremities. (3) 

Hence, the degree of openness of the larynx would not cause a dif- 
ference in the sounds, but only in the volume of the voice. (4) 

Very probably the third opinion is most correct, although the experi- 
ments first mentioned prove, that the vibrations of the vocal cords con- 
tribute less to produce the voice than those of the air passing through 
the glottis ; they occur simultaneously, without being necessarily con- 
nected with speaking, and the more as the larynx and trachea vibrate 
very evidently when the air is blown in with force, although the voice 
is not necessarily produced. (5) 

The acuteness of the voice in the female corresponds very well with 
the narrowness of the glottis, but not with the greater softness of the 
vocal cords. 

§ 2286. But although the voice forms in the larynx, particularly in 
the glottis, the parts, however, before this opening, the epiglottis, the 
cavity of the mouth, and the nasal fossa?, also assist to form it. 

Doubtless the principal function of the epiglottis is to close the la- 
rynx during deglutition, but very probably also it contributes to produce 
the voice. 

In fact Haller has refused to it, contrary to the opinion of Tau- 
vry,(6) and Santorini,(7) all agency in phonation, not because it exists 
before the fetus possesses a voice,(8) but because this latter is formed 
in the larynx, consequently below the epiglottis, and because birds sing 
although deprived of it. (9) 

This view of the subject is supported by some experiments, which 
demonstrate that the force of the voice does not change, although we 
cut transversely between the larynx and the hyoid bone, draw the 

(1) Ferrein, p. 566, 560. 

(2) Id., p. 559. 

(3) Ferrein, loc. cit.— Portal, E.rp. sur la voix ; in his Mtmoires, vol. ii., p. 308. 

(4) Ferrein, p. 558. 

(5) Liscovius, p. 34. 

(6) Nov. anat., Ulm, 1694, p. 408. 

(7) Oe laryngc,% 10. 

(8) Mayer, loc. cit., p. 185, 186. 

(9) Epiglottis equutem nihil facial ad coctm cum ea (vox)naia alt et perfecta 
quam primum aer ex glottidis rima prodiit et absque epiglottide ares suarissime 
variant (El phy*-, 1. ix., pt. )., § v., p. 572). 



OP THE ORGANS OP VOICE. 337 

epiglottis outward, and thus place the glottis directly opposite the 
external wound : that the removal of the top of this cartilage has no 
influence on the voice generally,(l) and that its depression, its eleva- 
tion, and even its entire removal, have no effect on the character of the 
sounds.(2) 

But these facts only demonstrate that the epiglottis is not absolutely 
necessary to phonation. Farther, the argument drawn from birds 
proves nothing, since their voice is formed in a lower larynx, and in 
them the epiglottis may be replaced by the whole trachea and by the 
superior glottis. 

Finally, several observations and experiments, made with great care, 
admit the conjecture that the epiglottis alone, or together with the soft 
palate, contributes materially to the changes in the volume, tone, and 
modulation of the voice, (3) since its situation, direction, and form ex- 
perience changes like those remarked in- this respect in the voice, and 
we have no authority for admitting that these phenomena result from 
other changes which occur in the larynx, an opinion probably pro- 
fessed by Ferrein,(4) since the new organ of voice he maintains can 
hardly be the soft palate. (5) 

In regard to the cavities of the nose and mouth we may remark, 
that the power and clearness of the voice are increased by its being 
retained in these two cavities, as is easily seen from the difference 
when the nose is stopped, or the pituitary membrane is swelled. 

Farther, the different inflexions of the voice, which are termed lel- 
ters,(6) are produced both by the larynx and the different parts of the 
oral cavity. 

The vowels are formed principally in the canal included between the 
tongue and the palate. Their differences depend almost entirely on 
those in the diameter of this canal, caused by the motions of the 
tongue. 

On the contrary, the epiglottis and the different parts of the mouth, 
especially the lips and the soft palate, have great effect on the forma- 
tion of the consonants. 

II. SEXUAL DIFERENCES IN THE LARYNX. 

§ 2287. The larynx is one of the organs which presents most mani- 
festly the differences of sex. That of the female is usually one third 
and sometimes one half smaller than that of the male ; all its con- 
stituent cartilages are much thinner : the thyroid cartilage also is even 
flatter, because its two lateral halves unite at a less acute angle. 

(1) Bichat, Anat. descript., vol. ii., p. 402, 401. 

(2) Liscovius, p. 34. 

(3) Mag-endie, Physiol., vol. i., p. 221.— Mayer, tec. cit.— Mcnde, loc. at. 

(4) Sur la formation de la voix ; in the Mem. de Paris, 1741, p. 574. 

(5) Haller, loc. cit., p. 455. .' 

(6) Kempelen, Mechanismvs der menschlichen Sprachc, nebst der Beschreibung 
seiner sprecaenden Maschine, Vienna, 1791. 



338 DESCRIPTIVE ANATOMY, 

Hence why the larynx in the male forms at the upper part of the neck 
a prominence which is not visible in the female. From the same 
cause also the groove in the.upper edge is much more superficial in 
this latter than in the male. 

The glottis in the female is much smaller than in the male, and the 
vocal cords are shorter. 



III. DIFFERENCES IN THE LARYNX DEPENDENT ON AGE. 

§ 2288. The sexual differences we are about to mention do not ap- 
pear until puberty : until then the larynx has precisely the same form 
in the two sexes, and consequently the voice is nearly the same in 
both. In eunuchs it is small as in females.(l) 

This organ developes itself much more slowly than other organs, 
and not proportionally w T ith them : it seems less regular in respect to 
its periods, so that the larynx is sometimes smaller in some children 
than in others who are younger, although the growth of the others 
corresponds perfectly to their age. 

The larynx, especially the glottis, generally continues small for a 
long time ; thus it differs but slightly in a child of three and one of 
twelve years of age. But the difference is suddenly so great at the 
period of puberty, that in the course of a year the glottis doubles in 
breadth and length. (2) 



IV. ABNORMAL STATE OF THE LARYNX. 
A. DEVIATIONS IN FORMATION. 

§ 2289. The whole larynx or some of its parts rarefy present pri- 
mitive deviations of formation. 

We, however, must mention here its unusual littleness, which de- 
pends on the permanence of its primitive formation, and which coexists 
with the destruction or imperfect development of the testicles,(3) the 
absence of the epiglottis,(4) the division of this cartilage,(5) the ab- 
sence of the upper horns of the thyroid cartilage,(6) of the cricoid and 
the arytenoid cartilages,(7) which is very curious as it establishes 
an uncommon resemblance between the larynx and the trachea : the 



(1) Dupuytren, Bull, de la soc. phil., vol. ii., p. 195. 

(2) Richerand, Recherch.es sur la grandeur de la glottc et sur Vitat de la tunique 
vaginale dans Venfance ; in the Mlm. de la soc. mid. d'imul, vol. iii. p. 326. 

(3) Dupuytren, Bull, de la soc. phil., vol. ii., p. 195.— Meckel, Handbuch der patho- 
logischen Anatomie, vol. i., p. 485. 

(4) Targioni Tozzetti, Prima raccolta, Florence, 1752. 

(5) Meckel, loc. cit. 

(6) Sandifort, Exerc. anat., 1. ii., ch. vii., p. C4. 

(7) Roederer, Defceluparalylico; in the Comm.soc. Gott. % vol. iv., p. 136. 



OF THE ORGANS OF VOICE. 339 

obliquity and curve of the epiglottis ;(1) the imperfect division of the 
larynx by a cord which is directed from above downward. (2) 

The consecutive deviations of formation, (3) especially those depend- 
ent on mechanical injury, are much more common than the primitive. 
We must distinguish among them wounds in the larynx made by a 
cutting instrument, in suicide. Wounds of the epiglottis are generally 
considered as fatal ; we however have one case before us, where this 
cartilage was entirely divided longitudinally, and also cut transversely 
in its right half ; but death did not ensue. This case is curious also 
as it proves what we stated above, that the epiglottis is not absolutely 
necessary to close the glottis. 

Wounds of the larynx are very frequently fatal, from their conse- 
quent irritation and inflammation, on account of its great sensibility. 

Sometimes death occurs at the end of a certain time, being caused 
by the abundant granulations which completely obstruct the glottis, 
and which are formed in consequence of a wound which suppurates. (4) 

The arytenoid cartilage is partially separated by a cutting instru- 
ment, and thus hanging in the glottis, may cause death by suffo- 
cation, like any other foreign body. (5) 

The cartilages of the larynx are not necessarily fractured in persons 
who die by hanging, although they are sometimes broken. (6) 

B. ALTERATIONS IN TEXTURE. (7) 

§ 2290. The mucous membrane of the larynx either alone or with 
that of other parts, particularly the cavity of the mouth and that of 
the trachea, is often inflamed. Sometimes there is effusion, and an 
accidental membrane is formed, which more or less completely closes 
the glottis, and the patient is suffocated. 

In phthisis laryngea also ulcers often exist which destroy it in 
a greater or less extent, and cause abnormal adhesions between it and 
the pharynx. This state also may cause suffocation in more than 
one way. But the swelling alone of the inflamed parts, without any 
effusion or ulceration, may be fatal. (8) 

(1) Atti di Siena, vol. iii., p. 232. 

(2) Meckel, Handbuch der pathologiscken Analomie, vol. ii., pt. ii,, p. 140. Ths 
case cited by Otto (Path, anqt., p. 223), of a larynx divided into three, does not refer 
to this, but to the trachea, which presented three branches instead of two (Sandifort, 
Exerc. ac, p. 65). 

(3) G. Bell, Cases of diseases and wounds of the larynx ; in his Surgical observa- 
tions, London, 1817, p. 1. 

(4) Bell, loc. cit., p. 44. 

(5) Ibid. 

(6) Morgagni cites one case of rupture of the cricoid cartilage (Ep. anat. mcd., 
vol. xix., p. 13). 

(7) Belt, loc. cit,— Howship, On the affections of the larynx ; in the Practical obser- 
vations in surgery, London, 1816, p. 14. 

(8) Howship, loc. cit., p. 153. 



340 DESCRIPTIVE ANATOMY. 

The cartilages of the larynx are more subject than any others to 
ossify, and consequently to be affected with all the diseases peculiar 
to the bones. 

Among the new formations cysts are not unfrequent in this organ, 
although much less common than the preceding anomalies. Some- 
times they belong to the class of hydatids ; there is more or less danger 
of suffocation from thern by closing the glottis. 

C. FOREIGN BODIES. 

§ 2291. As substances which pass into the stomach from the upper 
part of the alimentary canal must necessarily pass over the epiglottis, 
foreign bodies not unfrequently enter this organ, and thence pass into 
the trachea. This happens particularly when we talk while eating, 
as then the glottis is not closed. These foreign bodies soon occasion 
death by suffocation. A case however has been mentioned where a 
ducat continued two years in the larynx,(l) and another where a piece 
of a nut-shell as large as a finger-nail remained there seven years. (2) 



ARTICLE SECOND. 

ORGANS OF RESPIRATION. 

I. NORMAL STATE. 

A. LUNGS. 

I. PERFECT STATE IN GENERAL. 

§ 2292. The organs of respiration (systema respiratorium)(3) are 
the lungs, which communicate with the external air by the trachea. 
Beside the prolongations of the trachea, they are formed by the pulmo- 
nary arteries and veins, by lymphatic vessels, nerves, and cellular tis- 
sue between these two parts, and a serous envelop, the pleura. 

(9) Hoechstetter, Obs. med., dec. vi., c. x. 

(1) Tulp, Obs. tried., 1. ii., c. vii. 

(1) M. Malpighi, Dc pulmonibus epis/ol. I. ct II. ad A. Borellum, Bologna 1661 
—1 h. Bartholin, Be pulmnnum substantia et motu distribc. Ace. M Ma7pighii dc 
pulm. obs. anat., Leyden, 1672.— Helvctius, Observations sur le poumondel'komme • 
in the Mem.de Parts, 1718.— Wildrik, De fabricd pulmonum, Franeker 1761 — 
Wohlfahrt, Dc bronchus vasisquc bronchialibus, Halle, 1748.— Hildebrandt ' De pul- 
moriibus, Gottingen, 1786. — Reisseisseii, De putmomim structurd, Stra^burtr 1R(V? 
-Scemmerring and Reis.eissen Leber die Struetur die Vcrrichtung imd cten Ge- 
brauch dcr Lungcn, Berlin, 1808. b "' u '" t ' 1 wc 



OF THE RESPIRATORY SYSTEM. 341 



§ 2294. The lungs (pulmones) have the form of an irregular cone, the 
base of which looks downward and the summit upward. Their concave 
base rests on the diaphragm ; their very convex external face is turned 
towards the ribs ; the internal, which looks toward the heart, is con- 
cave. 

The anterior edge is blunt, the posterior is sharp. 

Each lung is divided into two triangular lobes, an upper, smaller, a 
lower, larger, by a deep groove which extends obliquely from above 
downward and from behind forward, and which passes entirely through 
it. Between these two lobes the right lung also presents a third, 
much smaller, which is situated forward, and contracts much from before 
backward. The left lung differs from that of the right side, as its 
lower edge presents a groove in which the lower part of the heart is 
situated. 

Beside this difference in the form, the right lung is a little larger and 
lower but broader than the left, and this in return is a little more elon- 
gated. 

Considered as a whole, the lung is divided into three, five, or six 
lobes, irregular in form and volume, in the spaces of which proceed 
the blood-vessels and the lymphatics, but the surface of which is not 
uneven, or but slightly so. 

§ 2295. The posterior edge of each lung is cleft in most of its 
length, and thus presents a depression, the upper half of which re- 
ceives the bronchise, the blood-vessels, and the nerves, while the liga- 
ments of the organ are attached to the inferior. 

The pulmonary artery is situated first entirely on the summit 
before the bronchia, and sends in this place a considerable branch 
to the lung ; but it is soon directed backward, and passes behind the 
bronchia. 

The pulmonary veins are found entirely forward and downward, 
excepting the smallest and lowest branches, which proceed behind the 
lowest ramifications of the bronchia?. 

B. SITUATION AND ATTACHMENTS. 

§ 2296. The lungs are situated on the two sides of the heart. Each 
is inclosed in a special serous sac termed the pleura, with the parietes 
of which they are in perfect contact in every part, but do not adhere, 
except at the part where this membrane is reflected to cover their ex- 
ternal face. 

Their upper extremity passes a little beyond the first rib. 

Vol. III. 44 



342 i>Esciurnv£ ana'k>:>iv 



The color of the lungs when a person is in good health, is grayish 
red, more or less spotted with black. 

D. TEXTURE. 

§ 2297. Among the different parts mentioned as composing the 
lung, the trachea is the base of the others, and also the most impor 
tant, as the air passes through it to enter and emerge from the lung. 

a. Trachea 

§ 2298. The trachea (tracheia el arteria aspcra) is a canal abouC 
four inches long and nine lines broad, which begins at the fifth cervi- 
cal vertebra, below the larynx, and is covered only by some muscles, 
particularly the sterno-hyoideus and the sterno-thyroideus. It is situ- 
ated exactly on the median line, passes directly before the esophagus, 
and descends directly into the chest, between the large vessels of the 
head. Thence it gradually inclines toward the right side, so that its 
left portion corresponds to the centre of the vertebral column, and di- 
vides at an obtuse angle behind the arch of the aorta, about opposite the 
third dorsal vertebra, into two lateral branches, termed bronchi or bron- 
chia. The light bronchia is generally eight lines broad, one inch 
long, and the left is about half an inch broad, and two long. The di- 
rection of this latter is more perpendicular than that of the other : it is 
situated between the descending vena-cava and the azygos vein. The 
left turns below the arch of the aorta, and goes forward. 

Each bronchia is covered with the pleura, proceeds obliquely from 
above downward, and from without inward, toward its corresponding 
lung, and on arriving there, divides into a superior and an inferior bron- 
chia, each of which proceeds to a lobe. The lower branch of the right 
bronchia also soon subdivides into two twigs, a superior, which is 
smaller, and an inferior, which is larger, for the middle and the in- 
ferior lobe. 

These canals ramify extensively within the lung, and represent a 
tree, terminated in every part of the surface of the organ in culs-de-sac, 
along which are distributed all the other component parts of the lung. 
The final ramifications, which are the most minute, and terminate in a 
cul-de-sac, are termed the pulmonary cellules (cellular puhnonares). 

§ 2299. The trachea is formed by very different parts, viz. by 
fibrous tissue, cartilages, muscular fibres, and a mucous membrane. 

a. Fibrous tissue. 

§ 2300. The fibrous tissue is composed of longitudinal fasciculi, 
which do not form a continuous membrane, but leave between them nu- 



OF THE UESriRATORY SYSTEM. 343 

merous oblong spaces. It constitutes the outer face of the trachea, and 
adheres intimately to the subjacent mucous membrane. Its vessels 
are more numerous than those in the other fibrous organs, and thus it 
resembles the fibrous tunic of the arteries. 

From the great elasticity of this tissue, the trachea contracts to its 
former dimensions, after being distended longitudinally. 

b. Cartilage. 

§2301. The fibrous tissue of the trachea and of its ramifications, 
inclose pieces of cartilage, placed successively from above downward, 
on the two faces of which it passes, and adheres intimately. It, how- 
ever, does not cover directly the surface of these cartilages, which are 
entirely developed by a special perichondrium. 

The form, dimensions, and situation of these cartilages, vary in dif- 
ferent parts of the trachea, and in its ramifications. 

In the trachea they form imperfect rings, open at their posterior part, 
which surround the anterior and lateral parts of the passage. These 
rings are about two lines high, half a line thick, and an inch and a half 
long. They circumscribe about the two thirds of the trachea when 
in its greatest state of distension, and more than three fourths of its 
circumference when it is collapsed. 

The number of its cartilages varies from sixteen to twenty. 

Their form is more regular and more constant at the centre of the 
trachea than at its upper and lower extremities. In most of this canal, 
they generally form rings of equal extent, and of about the same 
height. 

The first, on the contrary, is much higher than the others, and higher 
at its anterior than at its posterior part. This arrangement establishes 
rather a remarkable correspondence from before backward, between it 
and the cricoid cartilage, in which there is an opposite arrangement. 

This ring, also, is most generally united at its posterior extremity 
with the second whence results an undoubted analogy with the tvpe of 
the formation of the larynx. 

Sometimes there is a similar adhesion between the third and the 
fourth ring, either on both sides, or more commonly on one only. 

The lower rings, on the contrary, frequently present on one or both 
sides, a greater or less fissure, that is, one which sometimes extends to 
their lower extremity, and sometimes stops short of it. Frequently, 
but not always, we then remark on the opposite side, a small segment 
of an imperfect circle, which corresponds to one of the two halves 
formed by the division, or a ring cleft on the other side, which in some 
measure makes up for the want of symmetry. But we as commonly 
find there a common and perfect ring, or one which is partly divided 
in the same manner and on the same side. 

The rings of the loose portion of the bronchia; are generally similar 
to the final cartilaginous rings of the trachea. 



344 DESCRIPTIVE ANATOMY. 

There are generally but eight in the right bronchia, while there are 
eleven or twelve in the left. As they approach the lungs, they be- 
come more irregular, and are divided or blended with the rings ad- 
jacent. 

The number of the cartilages suddenly diminishes very much within 
the lungs, so that the ramifications of the bronchia; become more mem- 
branous there. But, at the same time these cartilages lose their re- 
gular form : they cease to represent rings, and resemble layers which 
are irregularly quadrilateral, triangular, &c. Besides, we find them 
in all parts of the trachea. 

They become smaller and rarer, in proportion to the gradual con- 
traction of the ramifications of the bronchia;. The last which are per- 
ceptible have a rounded form. 

We find none in those ramifications about one third of a line in 
diameter, or at least they are extremely small, and scarcely percep- 
tible. 

Finally, the last ramifications of the bronchiae are simply membra- 
nous, and some lines below the surface of the lung, we find no trace of 
cartilage. 

c. Muscular fibres. 

§ 2302. The posterior part of the trachea is formed by a muscular 
membrane,(l) which is about half a line thick when it is contracted. 
This membrane is composed only of transverse fibres, which are at- 
tached to the cartilaginous rings, and to the fibrous tissue between 
them, so as to cover the inner face of these rings, and of this tissue 
about from one to two lines. 

Within the lung, where the cartilages are arranged irregularly, and 
distributed on the whole extent of the bronchial tree, these muscular 
fibres surround also the whole trachea. They increase inversely as 
the cartilages, and they can be traced farther than these latter. 

d. Mucous membrane. 

§ 2303. The fibrous tissue and the muscular tissue of the trachea 
are covered in their whole extent by a thin mucous membrane, which 
forms a continuous sac, and adheres intimately to the adjacent parts. 

Its posterior face presents in the whole extent of the trachea, muci- 
parous glands, arranged compactly, which are more numerous and 
larger at the lower part of the trachea, where it bifurcates, and in the 
portion of the bronchiae and of the lungs. They are very near in these 
different parts, and they are frequently as large as a bean. 

They form a continuous layer, situated mostly behind the muscular 
membrane, between the fibres of which their very short excretory pas- 

(1) Eberhard, Diss, de musculis bronchialibus eorumoue in statu sano velmorboso 
actionc, Marburg, 1817. 



OF THE RESPIRATORY SYSTEM. 345 

sages penetrate. This layer extends uniformly on the portion of the 
trachea formed by muscular fibres, while the glands are principally 
collected between the cartilaginous rings, so that after removing 
these latter, we easily perceive the place they occupy by the spaces in 
the glandular layer. 

We must distinguish from these muciparous glands, the bronchial 
lymphatic glands (G. bronckiales), which are found in the same 
places. 

§ 2304. The mucous membrane is the last part visible among those 
which contribute to form the trachea and its ramifications, although 
reason and observation unite to demonstrate that its irritability extends 
beyond the points where its muscular texture disappears. 

The most minute ramifications of the trachea, which are formed by 
a homogeneous substance, terminate in a cul-de-sac, and are not con- 
tinuous, as Helvetius asserts, with the cellular tissue which unites the 
different organic parts of the lung. The trachea forms a hollow tree, 
the twigs of which communicate by the branches, and the latter by 
the trunks resulting from their union, but not by means of mucous tis- 
sue existing between these ramifications. This fact is established by 
numerous dissections and experiments. 

The minutest twigs of the bronchial tree, when filled with air or any 
other fluid, present the same form and the same limits, either when ex- 
amined with the naked eye, or with a microscope. If we fill a bron- 
chia with air or any other fluid, so as to inject, for instance, a whole 
lobe, and one of the secondary twigs is afterwards tied, the part of the 
lung in which this latter is distributed remains swelled and distended, 
while that where the bronchial twig is not tied soon collapses. 

b. Blood-vessels of the lungs. 

§ 2305. The blood-vessels of the lungs are of two kinds. Most of 
the organ is formed by the pulmonary arteries and veins, the first of 
which carry venous blood, while the veins carry back to the left half 
of the heart this fluid, which has been changed by the action of the air 
into arterial blood, in the limit between the two systems. 

The trunks of these vessels enter and emerge from the lungs at the 
same point.* 

Even within the organ the pulmonary veins are nearer the bronchise 
than the arteiies are. 

§ 2306. The second order of blood-vessels includes the bronchial 
arteries and veins {vasa bronchialia), which are connected with the 
nutrition of the lungs. We have already mentioned their origin. These 
vessels are distributed in the substance of the lung, along the ramifica- 
tions of the bronchiae, rest on their surfaces, and surround them with 
numerous plexuses. After supplying the muscular and the fibrous tis- 
sue, they penetrate to the mucous membrane, into which they send 
numerous ramuscules to the membranes of the pulmonary vessels, to 



346 DESCRIPTIVE ANATOMY 

the nerves of the lungs, and form a very minute and complex tissue on 
the surface of all these parts, below the pleura. 

It is very curious that the anastomoses occur, not only in this vas- 
cular net-work, but also between the considerable branches and twigs 
of the pulmonary and bronchial vessels. 

The bronchial veins even mostly empty into the pulmonary. Those 
of the roots of the lungs alone unite in small trunks, which empty into 
the azygos vein, or the descending vena-cava, or into the subordinate 
twigs of the sj^stem of the veins of the body. 

It follows then, from this arrangement : 

1st. That even in the normal state the vascular systems of black 
and red blood communicate extensively in the substance of the lung. 

2d. That analogous communications which appear in other parts as 
abnormal, as the termination of the coronary veins of the heart in the 
left ventricle, the insertion of one or more pulmonary veins into the 
vena-cava, the origin of a great pulmonary artery from the descending 
aorta, &c, are only a more marked development of this type. 

3d. That in the cases where the pulmonary artery was obliterated 
or very narrow, and the subjects hved a long time, these anastomoses 
were probably large enough to carry the blood in the pulmonary ar- 
teries. In fact, the bronchial vessels were found very much dilated in 
a case of this kind.(l) 

c. Lymphatic glands and vessels. 

§ 2307. We have already made known the most important facts in 
regard to the distribution of the lymphatic vessels iiuhe substance of the 
lung, and of the lymphatic glands which exist along the ramifications 
of the trachea. 

d. Nerves. 

§ 2308. The nerves of the lungs arise from the pneumogastric 
nerve. They are very small in proportion, but very numerous, and 
they can be traced far on the ramifications of the bronchiae. They are 
divided into two orders. Some are distributed in the bronchial tree 
others in the pulmonary vessels. The first penetrate to the muscular 
and mucous membranes, the second surround the vessels and pene- 
trate either into the substance of the great trunks, or into the capillaries. 
Some extend even to the pleura. 

c. Pleura. 

§ 2309. The 2)l eu ™ is a serous membrane, the outer portion of 
which, termed the costal pleura (pleura coslalis), covers the inner face 

<1) Jacobson, in the Deutschcs Archivfiir die Physiologic, \ ol. ii. p. 134. 



OP THE RESPIRATORY SYSTEM. 34*7 

of the pectoral cavity, while the internal or reflected layer, termed the 
pulmonary pleura (pleura pidmonalis), covers the external face of the 
lung. 

It adheres to the parietes of the chest less than to the surface of the 
lung : it however can be easily detached from this latter organ. 

It is composed of a right and a left sac (sacci pleura), which are 
separate and entirely distinct. 

The internal parietes of the external sac are not attached to the 
parietes of the pectoral cavity, but are turned towards each other, and 
form a septum which is directed from above downward, and from before 
backward, which divides the chest into a right and a left half. 

These two internal parietes, however, do not touch. They are sepa- 
rated in the centre, and in most of the septum they form, by the heart : 
backward, by the aorta, the esophagus, the azygos vein, and the tho- 
racic canal : forward by the thymus gland and the great vascular 
trunks. They are united in all these parts by very loose cellular tissue ; 
and are most remote from each other in their centre. That portion of 
the septum situated before and behind the heart, is termed the anterior 
and posterior mediastinum (mediastinum anterius et posterius). 

The anterior mediastinum descends between the heart and the 
middle anterior part of the thoracic cavity. Its direction is not perpen- 
dicular, but oblique from left to right. Besides, it does not correspond 
perfectly to the median line, but is thrown a little to the left, for the an- 
terior edge of the right layer is attached to the left edge of the sternum, 
and that of the left layer to the cartilage of the left ribs ; thence the 
mediastinum descends on the anterior face of the pericardium. 

The posterior mediastinum is more perpendicular than the anterior, 
and is situated between 'the anterior face of the vertebral column and 
the base of the heart. 

The external layer of the pleura of each side, is reflected on itself, 
between the two mediastina, to pass on the lower and upper faces of 
the lungs. For this purpose, it contracts around the pulmonary vessels 
and the bronchia^, and descends from the centre of the posterior edge 
towards the lung. Upward, forward, and backward, it contracts sud- 
denly, and from all parts towards this point ; but we observe below, on 
each side, a considerable triangular prolongation, terminated by a lower 
semicircular edge, which begins at the diaphragm, and is attached to 
the posterior edge of the lower lobe of the lung. This prolongation is 
termed the right and left ligament of the lung (I. pulmonis dextrum el 
sinistrum). That of the left side is much larger than that of the right. 

The pulmonary pleura covers the whole surface of the lung, even 
its lobes, but does not penetrate between these lobes, which are sepa- 
rated from each other only by cellular tissue. 



348 DESCRIPTIVE ANATOMY. 

/. Weight of the lung. 

a. Absolute weight. 

§ 2310. The sound lung of an adult male, with all the blood and 
the air it contains, weighs about four pounds. When removed from 
the body, the pressure of the external air, which had been prevented 
from acting on it, expels a considerable portion of this fluid which re- 
mained in it after the last expiration. 

Its weight then is to that of the whole body about as 1 . 35. 

b. Specific gravity. 

§ 2311. Considered in itself, the substance of the lung is heavier 
than water, for the lungs of a child which has never breathed sink in 
this fluid. But when respiration has commenced the specific weight 
of the organ is less than that of water, as the air which enters there is 
not entirely expelled during expiration. We cannot even press it out 
from a section of the lung : for then, after rupturing the ramifications 
of the bronchiae, it extends in the cellular tissue, so that at the end 
of the experiment the substance of the lung is still lighter than the 
water, although a little heavier than it was before.(l) 

g. Capacity. 

§ 2312. The capacity of the lung is not the same in all periods of 
life. It varies much, according as the organ is distended at the end 
of inspiration (inspiratio), or in that of contraction, at the end of expi- 
ration (expiratio): 

The estimates given by authors vary, which may arise from a real 
difference in the capacity of the lung and the nature of the modes 
employed to estimate it. 

In the first respect there are very great individual differences, which 
are mostly congenital, but which may be accidental, as when the lungs 
are but slightly used, for instance, in students. 

The capacity of the lung is determined by adding the quantity of 
air expelled during expiration with that which remains there after 
this act is completed. This calculation may be made in several dif- 
ferent ways. 

Three processes can be used to determine the quantity of air which 
enters the lung at each inspiration : 

1st. We may measure the enlargement of the lung in inspiration, 
and the contraction after expiration. 

(1) Allen and Pepys, Second paper on respiration; in the Phil, trans., 1809, p. 41. 



OF THE UESPIRAVORY SYSTEM. 349 

2d. We estimate the chancres which supervene during inspiration 
and expiration in a fluid in which the individual is situated. 

3d. We measure the quantity of the air inspired and expired, by 
inspiring from a vase which has teen measured, and expiring into 
another, the capacity of which is also known, or by the last proof 
alone.(l) 

At present the estimates of the quantity inhaled and expelled at 
each respiration varies much, from three to forty cubic inches. In 
fact, Abildgaard estimates it at three inches ;(2) Wurzer(3) and La 
metherie,(4) at eight or ten ; Keutsch,(5) between six and twelve ; 
Abernethy,(6) Lavoisier, Seguin,(7) and Davy,(8) at thirteen ; Bo- 
relh(9) and Goodwyn,(10) at fourteen; Kite,(ll) Allen, and Pe- 
pys,(12) at seventeen or eighteen ; Herholdt,(13) between twenty-five 
and twenty-nine ; Cavallo,(14) Jurin,(15) Sauvages,(16) Hales,(17) 
Maller,(18) Chaptal,(19) Bell,(20) Fontana,(21) Mcnzies,(22) and 
l.iicherand,(23) between thirty and forty cubic inches. 

In estimating the quantity of air remaining in the lung after expira- 
tion, the following circumstances are attended to : 

1st. After expiration, as long as the chest remains closed and the 
lungs are not removed, these organs contain more air than when sepa- 
rated from the body, because they collapse after opening the chest, and 
thus expel the air they contain. 

2d. It is very difficult to expel the air which remains in the lung, 
and it can never be completely removed by the greatest possible 
pressure. 

(1) Jurin, in Haller, El. phys., I. viii., s. iii. 

(2) Ncue Vcrsuchc uber das Athmcn und den Nutzen desselben ; in the Nordischcs 
Arcfiiv. fiir Natur-und Arzneywissenchqft, vol. i., pt. i., p. 2. — Abildgaard however 
asserts in another place (ibid., pt. ii., p. 206), that from two to seven, and sometimes 
even fifteen cubic inches enter. 

(3) Gunther, Darslellung, p. 28. 

(4) Journ. de physique, vol. xlvi.,p. 108. 

(5) De act. gaz oxygenii per pulm. rcsp., Copenhagen, 1800. 

(6) Essays, London, 1793, vol. ii., p. 144. 

(7) Memoir c sur la respiration, &c. 

(8) Researches concerning nitrous oxyd, London, 1800, p. 433. 

(9) De motu animalium, p. ii., prop. 81. 

(10) Recherches expirimcntales sur les effels que produiscnl sur les animaux vivans 
la submersion, la strangulation, &c, Paris, 1 798. 

(11) Veber WUdcrherstellung schcinbar lodter Mcnschcn, p. 19. 

(12) Loc. cit. 

(13) NordisclUs Archiv., vol. i., pt. ii., p. 207. 

(14) Veber Anwendung der Gasartcn. 

(15) Diss. phys. math., London, 1732, diss. iv. ; in Haller, De part. corp. hum. Jab., 
vol. vi., p. 325. 

(16) In Haller, El. phys., vol. iii., p. 234. 

(17) Statical essays, vol. i., p. 238. 

(18) El. phys., vol. iii., loc. cit. 

(19) Chemie; in Bostock, Veber das Athmcn, p. 189. 

(20) Anatomy, vol. ii., p. 193. 

(21) Phil, trans., 1799, p. 319. 

(22) De rcspiralionc, Edinburgh, 1790. 

(23) Physiologic, vol. i., p. 374. 

Vol. III. 45 



350 DESciuriivE anatomy. 

Several methods have been proposed to estimate the quantity of air 
which remains in the lungs after expiration. 

1st. After fixing the diaphragm as firmly as possible, the abdomen 
is tied and the lungs collapsed, by making an incision in the panetes 
of the chest, we fill the space between these parietes and the organ 
with water, which it is asserted should be equal in quantity to that 
of the air expelled from the lung by the pressure of the liquid, and 
also that of the external air introduced into the chest through the 
parietes. 

2d. On opening the lung the air is received from it in a bladder 
adapted to the trachea, and it is measured ;(1) the lung is then im- 
mersed in water, the specific gravity of which is about equal to that 
of distilled water, while its absolute weight is known : the quantity 
displaced is weighed, and we determine the cubic quantity of air it 
still includes. 

From these two methods we may conclude the quantity of air re- 
maining in the lung of an adult after a complete expiration to be about 
one hundred and ten cubic inches. In fact, Goodwyn has introduced 
from ninety to one hundred and twenty cubic inches of water in the 
space between the chest and the lung. 

In Allen and Pepys' experiments, the quantity of air first collected 
was 31.580 cubic inches: the lungs, which weighed four pounds, 
and which from their weight occupied as much space as an equal 
quantity of water, displaced six pounds of the liquid, so that there still 
remained within them a quantity of air equal to an ounce of water, 
that is, 59.554 cubic inches. The total of these two sums- gives a 
little more than ninety-one cubic inches, as the quantity of air remain- 
ing in the lung after expiration ; but we may admit it as about one 
hundred and ten, on account of the pressure of the water on the mass 
of the lung, and the higher temperature during life. 

If we add to these one hundred and ten cubic inches of air remaining 
in the lung after a common expiration, about thirty inches which leave 
the organ at each common expiration of a healthy adult,(2) we shall 
have one hundred and forty-five inches as the capacity of the lungs 
in common inspiration, so that the difference of capacity between 
the state of dilatation and collapse of the organ is about thirty-five 
inches. 

But this difference increases very much when the respiration being 
deeper, the lung is unusually dilated and collapsed, because more air 
enters and leaves the lung at each time. 



8 



SI) Cline, in Allen and Pepys, Ioc. cit. 
2) We take this as the mean number : it seems to us that a lower estimate should 
be ascribed to an unusual smallness in the lung, or to careless calculation, and that a 
greater estimate depends upon an unusual development of the chest, or on a very 
deep respiration. Farther, we ought to mention that the air is dilated one sixth by 
the neat of the body. 



Thus Seguin(l) inhalecin a »»y rieea respiation one hundr^ «^<* 
thirty inches f air, whichwould expand yfe'.--- t neT>ody to 
one hundred ana fif ty so ^ then lhe ca , c7 ^ of the Jung was equal 
to two hundred and sixv-, cu ya c inches estimates the capacity 

9 i three hundred cubic inches 

On the other hand, Jurin exphv tW0 handred and twenty cubic 
inches,(2) and Herholdt, 208.(3) we admit nere tnat tnese expira- 
tions took place after a full inspi on ' we ou g ht t0 reduce the capa- 
city of the lung to fifty-two r 1 even t0 fort y cubic inches, which 
estimate perfectly agrees w ; tnat f° rrae d by Davy by another 
method.(4) 

In contrasting the estima* of Seguin and Jurin, and disregarding 
the diminution of the volur of tne air expired, we find a difference of 
two hundred and twenf Detween tne greatest dilatation and the 
greatest relaxation of iun S> that is, this latter state is to the 
other as 1 : 6.5. 

h. Force of the lung. 

§ 2313. The lun» s not very sensible. Its transverse and its lon- 
gitudinal muscular ' res > which are similar in their nature to muscles, 
give it the power o? ontr acting, which, judging from experiments,(5) 
is exerted whenev* i ts external or internal surface is stimulated, and 
which without s ti ulat i° n ( 6 ) executes the motions which cannot be at- 
tributed to those tfte parietes of the thorax, since they are simultane- 
ous with these )- ter > and are observed when the parietes of the thorax 
are destroyed. ) Consequently the air passages contract actively 
during expira jn j(®) but au " these phenomena, adduced to prove that 
the luno-s p'Sess a power of extension which allow them to dilate 
actively inspiration, can be satisfactorily explained in another 
manner. (9 

(1) oi r vations g&ntralcs sur la respiration ct sur la chaleur animate ; in the 
Joum. { physique, 1790, p. 467. 
/2) i Haller, loc. cit., p. 326. 
/3) -iOC. cit., p. 41. 
(4'L,oe. cit., p. 409. 

n Varnicr, in the Mem. de la me. roy. de mcd., ann. 1779. 

,b) Rudolphi, Uebcr das Atliemholen ; in his Anat. phys. Abhandlungen, p. 111. — 
•lormann, ibid., p. 110. 

(7) Bremond, Experiences sur la respiration ; in the Mim. de Paris, 1739, p. 455. 
— This author however adduces as proofs several phenomena which are by no means 
conclusive. 

(8) J. Carson, Memoirc sur Vilasticite dcs poumons ; in the Arch. gen. de mid., 
vol. ii., p. 134. 

(9) J. D. Herholdt, Ueber die chirurgischc Bchandlufigen dcr Brustwunden, 
veranlasst durch neue Versvchc uber den Mechanismus des Athemholens ; in the 
Nardisches Archiv., vol. ii., pt. i., p. 44-GO. 



352 uESCRU'TIVE i,NATOn\ 

f txuk tion of the luig. 

§ 2314. The function))! - } . reepira ^ f^^^J" 
sentially in the change of vent * £gh blood by the cxpul^ n 
of carbon and the absorption of L The atmospheric air enters 

into the organ daring inspiration,^ emerges from it loaded with 
carbonic acid during expiration ; this e of t } ie blood, and the cold 
produced by the evaporation of the \ ex i Tcl \ c d, are the most im- 
portant functions of the lungs ; but tK ar j alions i n its capacity also 
affect the circulation, for the blood crrt ales more rapidly from the 
Tight half of the heart into the pulmonic arter y during inspiration, 
and from the pulmonary veins into the lefi ort i on f tne heart during 
expiration. 

II. SEXUAL DIFFERENCES. 

§ 2315. The lungs of the male are larger trV t hose of the female, 
and the latter are more oblong than those of th^ e 

III. DIFFERENCES DEPENDENT ON DETELO. ENT 

A 

§ 2316. The lung presents considerable periodicijjifjf er ences,(l) in 
respect to its existence, situation, texture, color, con^ tSj volume, and 
finally its absolute and relative weight. 

1st. Existence. The lung is one of the last organ^ a p pe ar. It 
begins to be distinctly seen about the end of the second >onln of preg- 
nancy. 

2d. Situation. From the greater proportional volume { me heart 
and its slight development, the lung is situated much rnor^Qsteriorly 
before than after birth, so that sometimes it is not seen at all ^ opening 
the cavity of the thorax ; consequently it covers the pericaro irn) an d 
generally does not entirely fill the sac of the pleura, and heL a0 cs 
not touch the parietes of the chest. 

3d. Texture. At the third month of pregnancy we begin to Ly^. 
guish the cartilaginous tissue in the air- passages of the lungs. ^ n e 
lobules are at first united by a looser cellular tissue than that co». 

(1) Meckel, Mimoire sur le divcloppemcnl du cceur et dcs poumons dans les mam- 
miferes ; in the Journ. compl. dessc. mid., vol. i., p. 259. — Consult also on the differ- 
ence in the lung of the child before and after respiration, G. J. Schmitt, Xeue Ver- 
suche und Erjahrungcn uber die Plocquetsche und hydrostatische L/ungenprobc, 
Vienna, 1806. — A. Lecieux, Considerations medico-Ugalcs sur I' infanticide, Paris, 
1811. — Magendie. Sur la structure du poumon dc I'homme, sur let modifications 
qu'e'prouve cette structure dans les divers ages, el sur la premiere origine de la 
phthisie pulmonaire ; in the Journ. de physiol. c.vpirim., vol. i., p. 78. — Fleischmann, 
Sur la formation de la trachee-artere ; in the Journ. compl. du diet, des sc. mid., 
vol. xvi., p. 141.— Id., De chondrogenesi asperice arterice etdesilu oesophagi abnormi 
nonnulla, Erlangen, 1820. 



OF THE RESPIRATORY SYSTEM. 353 

rnonly seen, and they are also formed of small subordinate lobes, so 
that here, as in other parts, as the muscles, the homogeneous mass is 
at first divided into its great subdivisions, but afterward into the 

Smaller parlo. 

4th. Color. The color of the lung is at first reddish white in the 
fetus, and is whiter the younger the fetus is. This organ gradually be- 
comes of a deeper red, in proportion as it is better supplied with blood. 
After birth this tint is w^ t from reS piration, and also becomes 
deeper. At twenty years the lun fe ; mottled with Uue and 

black spots and from this time its color belo m dark gQ thftt 
in advanced life it is more or less generally black or Dicao, y^ij^ 

5th. Contents. The trachea and its ramifications contain alte/ t; r th 
only air, and % small quantity of aqueous vapor and mucus. But this 
is not true of the fetus, where it is filled with the fluid of the amnion. 
By the lavs of hydraulics, when the fetus swims in this fluid it enters 
the trachea, without any respiratory motion on the part of the fetus. 
It usualy escapes after birth, and when it does not escape at this time 
which is rare, it may suffocate the child.(l) 

6t*. Volume. The lung is at first much smaller ; it occupies much 
les? space than the heart, and is easily blended with the very dilated 
au'icles of this latter. 

It does not acquire its normal proportional size till puberty. 

7th. Weight. The absolute weight of the lung presents very re- 
markable periodical differences, which depend on the organ remaining 
inactive until after birth. In the fetus its specific gravity is greater 
than that of water, in which it sinks ; but when respiration has once 
commenced, as it is never free from the air which has entered in it, its 
specfic gravity is less than that of the water, and it floats. 

§ 2317. Most of the differences mentioned, especially those in regard 
to situation, volume, color, and specific gravity, appear more or less at 
birth, and result from respiration. 

The lung, becoming lighter from the effect of the air entering it 
and which never entirely leaves it, occupies also more space after res- 
piration, and is situated more anteriorly, covers most of the pericar- 
dium, and is in contact with the parietes of the chest. The deep red 
color communicated to it by the venous blood before respiration, 
changes to a bright red when the new being breathes. 

Finally the organ, which when collapsed received less blood, and 
was consequently lighter, becomes heavier when after being distended 
by respiration, it is more permeable to the blood. 

Hence these differences have been thought sufficient to determine 
whether an infant was born living or dead. But as the specific gra- 
vity having diminished, the lung floats, which proof constitutes what is 

(1) P. Schecl, Commentatio dc liquoris amnii asperice arteries fcetuum humanorum 
na.tu.ra et usu ejusque in asphyxium neonatorum ct medicinam furensem injtuxu, 
Copenhagen, 1799.— Herholdt, in Reil, Arrhiv.fur die Physiologic, vol. iii., p. 163.— 
Id., in the Nordischcs Archiv., vol. i., p. 212. 



354 DESCRIPTIVE ANATOMY. 

termed the test hydrostalica ;(1) as also the afflux of the blood in- 
creases the absolute weight of the organ, and its relative weight 
compared to that of the body constitutes another kind of proof, termed 
the test by the balance,{2) this principle ha= boc» Uid down that 
when the lungs of a child swim in water, and a similar or analogous 
proportion exists between the relative weight of the lungs and that of 
the body, it is established that this child was born ahve and that it 
breathed. , . . 

Considered generally and ab?ni-«fy, these conclusions are correct ; 
but great emd important ^notions are necessary. 

1st. The li'-s" ma .y become lighter by respiration, and the child 

not be ^ m - 

2d. The lungs may swim from some other cause than respiration. 

3d. Respiration does not necessarily produce this change in them. 

4th. The lungs sometimes have a greater absolute weight, although 
respiration has not taken place. 

5th. On the other hand, they may present after respiration a specific 
gravity as great as that they possess, according to the general opinion, 
before this act. 

In fact : 

1st. The infant sometimes breathes sufficiently during parturition 
to render its lungs capable of swimming, although it may be still- 
born.^) 

2d. The lungs may also swim from the fact that the air has been 
pushed into them, through the mouth or nose, either while they con- 
tinued in the thorax, or after their removal from this cavity. Putre- 
faction also may give rise to the same result. 

3d. Several experiments demonstrate that respiration does not ne- 
cessarily cause in the lungs the above mentioned changes. Some 
parts of a lung, or even an entire lung, have been seen which did not 
swim in water, although the child has lived, breathed, and cried, not 
only for several days, (4) but even for six weeks. We have seen in a 
child six weeks old all the middle lobe of the right lung, and in ano- 
ther four weeks old, great portions of the same lobe apparently healthy, 
which were absolutely incapable of floating. 

The left lung is most frequently retarded in its development, which 
peculiarity doubtless depends on the fact that the right bronchia is 
much shorter and broader than the left, so that usually, even in chil- 
dren who died soon after birth, the right lung floated, while the left 
floated very imperfectly, or not at all.(5) 

(1) F. Albert, De docimasid pulmonum hydrostaticd, Halle, 1791 

(2) G. G Plocquet, Comm. med. in processus criminates super homicidio, infanti- 
eidio et embryoctoma, Strasburg-, 1 787. ' l "-/ a "" 

(3) Schmitt (loc. eit., p. 150-176) has reported examples of this. 

(4) Kaltschmied, De e.rp. pulm. infant, aq. injectis, ann 1751 

(5) A. Portal. Memoire dans lequel on dtmontre V action du poumon svr Vaorte 
pendant It tempt de la respiration, et oil Von prouvc que, dans V enfant qui rientde 



oi l'H£ RESPIRATORY SY8TEM. 355 

It is at l*"^ ver y rare that the contrary occurs. 

a. The rarest case is when the cause of the sinking of the lung 
depends on a morbid alteration in its texture, an effusion, an indura- 
tion, for these are very unfrequent before birth, and even when they 
occur to a great extent, the organ does not acquire a greater specific 
gravity than that of water. 

6. A more common cause is the presence of foreign bodies, espe- 
cially mucus, and the fluid of the amnion in the trachea, or the feeble- 
ness of the fetus, all which circumstances render the dilatation of the 
lung imperfect. 

c. We must remark also that this change in the specific gravity 
supervenes gradually, and when the respiration takes place with the 
requisite degree of strength, as in the beginning, and when the child 
respires but feebly, it extends to some parts of the lung only, and 
sometimes it is not produced at all by the first inspirations. 

4th. Sometimes, although the child has not breathed, the lungs 
have an absolute and consequently a relative weight, in proportion to 
the body, as great as when the child has respired. There are some 
cases where the relation between the weight of the lung and the body 
is still greater, for instance, as 1 : 151, to 29§§, to 33f , to 32^, to 
34_7_s_ (i) although respiration did not take place. 

This circumstance is still more curious, as the lungs contained also 
more blood than usual. 

Mh. Observation likewise proves that the lungs of infants born alive 
are sometimes proportionally lighter than those of still-born children 
are. according to the preceding estimate,(2) as they are found in the 
proportion of 1 : 77 T 9 T) to 77a§, and to 104. 

II. ABNORMAL STATE. (3) 

§ 2318. Primitive deviations of formation. The lungs present pro- 
portionally but few anomalies resulting from a primitive deviation of 
formation ; they however sometimes manifest them in respect to quan- 
tity and quality. 

1st. The congenital anomalies in regard to quantity are generally : 

a. Deviations of formation from an arrested development. Here 
are arranged particularly : 

a. The absence of the trachea, of a lung, or of the two lungs ; this 
last anomaly usually attends acephalia vera ; the second is more rare, 

naltrc, Ic poumon droit respire avant legauche ; in the Mim. de Paris, 1765. — Some 
writers have attributed this discovery to Petit, but wrongly : he mentions only 
one case (Mim. de Paris, 1753), and does not point out the real cause of the pheno- 
menon. 

(1) Schmitt, loc. cit., p. 138. 

(2) Id., ibid. 

(3) Van den Bosch, Commentatio exhibens anatomiam syslemalis respirationi in- 
scrvicntis pathologicam, Harlem, 1801. 



356 DESCRIPTIVE ANATOMY. 

and also occurs in subjects whose formation is otherwise normal, and 
resembles the normal singleness of the lung in several serpents. The 
absence of the trachea is less common than that of the lungs ; \*hen 
it occurs the lung is situated next to the larynx, as also in sevenJ 
reptiles. 

b. Narrowness and closing of the trachea, which has been observed 
when the skull was deficient.(l) 

c. The smallness of one or of the two lungs. The first anomaly is 
generally produced mechanically by an external obstacle, particularly 
the presence of the abdominal viscera in the cavity of the thorax in a 
subject affected with diaphragmatic hernia. The second, which is 
generally connected with narrowness of the thoracic cavity, depends 
on a primitive dynamic anomaly of the formative power, and some- 
times occurs in individuals otherwise well formed, and sometimes is 
attended with other deviations in formation, arising from suspended 
development. 

d. We ought also to mention here the exposure of the lungs 01 
trachea sometimes observed, since it depends upon the formation of the 
parietes of the thorax being arrested at one of the early periods 
through which it successively passes. 

b. The great size of a lung, attended generally by the deficiency of 
the other, results from an excessive action in the formative power. 
2d. Congenital deviations in form relative to the quality are : 

a. The abnormal division, which is indicated in the lungs by vhe 
presence of an unusual number of lobes, or by the deeper separation of" 
those always existing, and in the trachea by its division into three 
branches. This last anomaly, judging from facts hitherto collected 
occurs only on the right side, and is curious as a repetition of the pecu- 
liar structure of the ruminantia and the cetaceous animals. 

b. An opposite anomaly occurs when the lungs are not divided into 
lobes as usual, or when this division is not clearly indicated. 

c. Lateral inversion is where the right lung has but two lobes and 
the left three. This anomaly commonly occurs only when there is a 
general lateral inversion. 

Consecutive deviations of formation. The pure consecutive accidental 
deviations of formation are particularly wounds, which often suddenly 
cause death, on account of the considerable caliber of the vessels, but 
sometimes death occurs from the dangerous inflammation and suppu- 
ration of such important organs ; but they are not necessarily nor 
always fatal. 

We must mention here the abnormal communication with the other 
cavities, which sometimes occurs when the parietes are destroyed ; 
the most remarkable is that which occurs in aneurism of the aorta. (2) 

(1) Otto, Monst. sex. disq., p. 10, 11. 

(2) Richerand, Observations sur I'ouvcrturr. des aneurysmrr, de Vaortc dans la 
irarhee-arlcre ct dans les branches; in the Mem. de la sue. mid. d'cmul., vol. iv., 
p. 545. 



OF THE RESPIRATORY SYSTEM. 357 

In this case, from the respective situation of the parts, the opening 
usually corresponds to the lower part of the trachea, or to the left 
bronchia. 

§ 2319. Alterations in texture. They are : 

1st. Inflammation, generally termed pneumonia, bronchitis, and 
pleuritis, according as the whole substance of the lung, the mucous 
membrane of the trachea, or the pleura, is affected. (1) 

The most usual consequences of pneumonia are : 

a. Thickening and induration of the tissue of the lungs, from an 
effusion often existing in a great degree, and then forming the state 
termed hepatization (hepatisatio)(2) The substance of the .lung is 
then generally homogeneous, friable, brittle, grayish white, much 
thicker in texture, and sometimes possesses a specific gravity greater 
than that of water. 

2d. Suppuration. Pus usually burrows for itself a passage into the 
bronchia. More rarely it is effused into the chest, constituting empyema, 
or into the adjacent organs, as the pharynx or the aorta. (3) 

Bronchitis terminates sometimes by suppuration, sometimes by the 
formation of solid or hollow membranes, which fill this cavity and rarely 
adhere to its inner face. Very probably, however, the development of 
these accidental membranes is not always and necessarily preceded 
by an inflammation of the trachea. (4) 

The consequences of pleuritis are : 

(1) C. Hastings, A treatise on inflammation of the mucous membrane of the lungs, 
London, 1820. — T. Alcock, Observations on the inflammation of the mucous mem- 
brane of the organs of respiration, London, 1820. 

(2) Bricheteau, De V hepalisation pulmonaire ; in the Journ. compl. des sc. mid., 
vol. ix., p. 106. 

(3) V. Laennec, De V auscultation mediate, vol. i. — Andral, Clinique midicale, vol. 
ii. — Louis, Observations relatives d la perforation du parenchyme du poumon ; in the 
Archiv. gin. de m'ed., vol. v., p. 321.— Bouillaud, Nouvelles observations sur la gan- 
grene des poumons ; in the Revue midicale, vol. iv., p. 375. 

(4) This proposition cannot be admitted. It rests upon a fact mentioned first by 
Bayle, and since enlarged upon by Andral, that sometimes in individuals af- 
fected with chronic bronchitis, even with an expectoration of pus, the mucous mem- 
brane is hardly rosy or even perfectly white in its whole extent. But ought